This commit fixes the following golint warnings:
pkg/api/avatar/avatar.go:229:12: should omit type *http.Client from declaration of var client; it will be inferred from the right-hand side
pkg/login/brute_force_login_protection.go:13:26: should omit type time.Duration from declaration of var loginAttemptsWindow; it will be inferred from the right-hand side
pkg/metrics/graphitebridge/graphite.go:58:26: should omit type []string from declaration of var metricCategoryPrefix; it will be inferred from the right-hand side
pkg/metrics/graphitebridge/graphite.go:69:22: should omit type []string from declaration of var trimMetricPrefix; it will be inferred from the right-hand side
pkg/models/alert.go:37:36: should omit type error from declaration of var ErrCannotChangeStateOnPausedAlert; it will be inferred from the right-hand side
pkg/models/alert.go:38:36: should omit type error from declaration of var ErrRequiresNewState; it will be inferred from the right-hand side
pkg/models/datasource.go:61:28: should omit type map[string]bool from declaration of var knownDatasourcePlugins; it will be inferred from the right-hand side
pkg/plugins/update_checker.go:16:13: should omit type http.Client from declaration of var httpClient; it will be inferred from the right-hand side
pkg/services/alerting/engine.go:103:24: should omit type time.Duration from declaration of var unfinishedWorkTimeout; it will be inferred from the right-hand side
pkg/services/alerting/engine.go:105:19: should omit type time.Duration from declaration of var alertTimeout; it will be inferred from the right-hand side
pkg/services/alerting/engine.go:106:19: should omit type int from declaration of var alertMaxAttempts; it will be inferred from the right-hand side
pkg/services/alerting/notifier.go:143:23: should omit type map[string]*NotifierPlugin from declaration of var notifierFactories; it will be inferred from the right-hand side
pkg/services/alerting/rule.go:136:24: should omit type map[string]ConditionFactory from declaration of var conditionFactories; it will be inferred from the right-hand side
pkg/services/alerting/conditions/evaluator.go:12:15: should omit type []string from declaration of var defaultTypes; it will be inferred from the right-hand side
pkg/services/alerting/conditions/evaluator.go:13:15: should omit type []string from declaration of var rangedTypes; it will be inferred from the right-hand side
pkg/services/alerting/notifiers/opsgenie.go:44:19: should omit type string from declaration of var opsgenieAlertURL; it will be inferred from the right-hand side
pkg/services/alerting/notifiers/pagerduty.go:43:23: should omit type string from declaration of var pagerdutyEventApiUrl; it will be inferred from the right-hand side
pkg/services/alerting/notifiers/telegram.go:21:17: should omit type string from declaration of var telegramApiUrl; it will be inferred from the right-hand side
pkg/services/provisioning/dashboards/config_reader_test.go:11:24: should omit type string from declaration of var simpleDashboardConfig; it will be inferred from the right-hand side
pkg/services/provisioning/dashboards/config_reader_test.go:12:24: should omit type string from declaration of var oldVersion; it will be inferred from the right-hand side
pkg/services/provisioning/dashboards/config_reader_test.go:13:24: should omit type string from declaration of var brokenConfigs; it will be inferred from the right-hand side
pkg/services/provisioning/dashboards/file_reader.go:22:30: should omit type time.Duration from declaration of var checkDiskForChangesInterval; it will be inferred from the right-hand side
pkg/services/provisioning/dashboards/file_reader.go:24:23: should omit type error from declaration of var ErrFolderNameMissing; it will be inferred from the right-hand side
pkg/services/provisioning/datasources/config_reader_test.go:15:34: should omit type string from declaration of var twoDatasourcesConfig; it will be inferred from the right-hand side
pkg/services/provisioning/datasources/config_reader_test.go:16:34: should omit type string from declaration of var twoDatasourcesConfigPurgeOthers; it will be inferred from the right-hand side
pkg/services/provisioning/datasources/config_reader_test.go:17:34: should omit type string from declaration of var doubleDatasourcesConfig; it will be inferred from the right-hand side
pkg/services/provisioning/datasources/config_reader_test.go:18:34: should omit type string from declaration of var allProperties; it will be inferred from the right-hand side
pkg/services/provisioning/datasources/config_reader_test.go:19:34: should omit type string from declaration of var versionZero; it will be inferred from the right-hand side
pkg/services/provisioning/datasources/config_reader_test.go:20:34: should omit type string from declaration of var brokenYaml; it will be inferred from the right-hand side
pkg/services/sqlstore/stats.go:16:25: should omit type time.Duration from declaration of var activeUserTimeLimit; it will be inferred from the right-hand side
pkg/services/sqlstore/migrator/mysql_dialect.go:69:14: should omit type bool from declaration of var hasLen1; it will be inferred from the right-hand side
pkg/services/sqlstore/migrator/mysql_dialect.go:70:14: should omit type bool from declaration of var hasLen2; it will be inferred from the right-hand side
pkg/services/sqlstore/migrator/postgres_dialect.go:95:14: should omit type bool from declaration of var hasLen1; it will be inferred from the right-hand side
pkg/services/sqlstore/migrator/postgres_dialect.go:96:14: should omit type bool from declaration of var hasLen2; it will be inferred from the right-hand side
pkg/setting/setting.go:42:15: should omit type string from declaration of var Env; it will be inferred from the right-hand side
pkg/setting/setting.go:161:18: should omit type bool from declaration of var LdapAllowSignup; it will be inferred from the right-hand side
pkg/setting/setting.go:473:30: should omit type bool from declaration of var skipStaticRootValidation; it will be inferred from the right-hand side
pkg/tsdb/interval.go:14:21: should omit type time.Duration from declaration of var defaultMinInterval; it will be inferred from the right-hand side
pkg/tsdb/interval.go:15:21: should omit type time.Duration from declaration of var year; it will be inferred from the right-hand side
pkg/tsdb/interval.go:16:21: should omit type time.Duration from declaration of var day; it will be inferred from the right-hand side
pkg/tsdb/cloudwatch/credentials.go:26:24: should omit type map[string]cache from declaration of var awsCredentialCache; it will be inferred from the right-hand side
pkg/tsdb/influxdb/query.go:15:27: should omit type *regexp.Regexp from declaration of var regexpOperatorPattern; it will be inferred from the right-hand side
pkg/tsdb/influxdb/query.go:16:27: should omit type *regexp.Regexp from declaration of var regexpMeasurementPattern; it will be inferred from the right-hand side
pkg/tsdb/mssql/mssql_test.go:25:14: should omit type string from declaration of var serverIP; it will be inferred from the right-hand side

Fixes #11758

Explore: add support for multiple queries

* docs: further documents changes to the docker image.
* docs: explains the changes to user id better.

* notification-service-refactor2:
  fix: removed log calls used while troubleshooting
  refactor: refactoring notification service to use new service registry hooks

Explore UI skeleton

* adds +/- buttons to query rows in the Explore section
* on Run Query all query expressions are submitted
* `generateQueryKey` and `ensureQueries` are helpers to ensure each
 query field has a unique key for react.

* refator: refactored PluginManager to be a self registering service, a lot more work needed to fully make plugin manager use instance variables and not so many globals

revert renaming of unit key ppm

* extensions: import and build

* bus: use predefined error

* enterprise: build script for enterprise packages

* poc: auto registering services and dependency injection

(cherry picked from commit b5b1ef875f905473af41e49f8071cb9028edc845)

* poc: backend services registry progress

(cherry picked from commit 97be69725881241bfbf1e7adf0e66801d6b0af3d)

* poc: minor update

(cherry picked from commit 03d7a6888b81403f458b94305792e075568f0794)

* ioc: introduce manuel ioc

* enterprise: adds setting for enterprise

* build: test and build specific ee commit

* cleanup: test testing code

* removes example hello service

#11211 removed the unit key ppm in favor of conppm. A change which is not forward compatible.
This commit revert the unit key back to ppm.
Also adds some better error description if trying to use a unit which don't exists.
Fixes #11743

* mjtrangoni-fix-deadcode-issues:
  tech: removes unused code
  add deadcode linter to circleci
  pkg: fix deadcode issues
  build.go: fix deadcode issues

Merge branch 'fix-deadcode-issues' of https://github.com/mjtrangoni/grafana into mjtrangoni-fix-deadcode-issues

* 'fix-deadcode-issues' of https://github.com/mjtrangoni/grafana:
  add deadcode linter to circleci
  pkg: fix deadcode issues
  build.go: fix deadcode issues

fix so that google analytics script are cached

prometheus: variable query should fallback correctly to a series query 

sql tsdb: fix value columns conversion to float when using timeseries query

fix misalignment of unit and other drop downs in firefox

removed height 100% from panel-container to fix ie11 panel edit mode

Add weback-dev-server with hot/hmr support

Using a query of for example up or up{job=job1}