Explore: Add history to query fields

* build: makes the grafana docker image smaller.

* build: branches and PR:s builds the docker image.

Mssql: add logo

unix socket docs

- _.reverse() was modifying state.history

- queries are saved to localstorage history array
- one history per datasource type (plugin ID)
- 100 items kept with timestamps
- history suggestions can be pulled up with Ctrl-SPACE

Merges the Grafana docker build into the main repository.

* Explore: facetting for label completion

- unified metric and non-metric label completion
- label keys and values are now fetched fresh for each valid selector
- complete selector means only values are suggested that are supported
  by the selector
- properly implemented metric lookup for selectors (until the first
  metric was used which breaks when multiple metrics are present)
- typeahead tests now need a valid selection to demark the cursor

* Fix facetting queries for empty selector

Karma to Jest: variable_srv

Karma to Jest: OpenTSDB datasource

Karma to Jest: remove tests

* Add click on explore table cell to add filter to query

- move query state from query row to explore container to be able to set
  modified queries
- added TS interface for columns in table model
- plumbing from table cell click to datasource
- add modifyQuery to prometheus datasource
- implement addFilter as addLabelToQuery with tests

* Review feedback

- using airbnb style for Cell declaration
- fixed addLabelToQuery for complex label values

[skip ci]

Add auto_assign_org_id to defaults.ini

For #12801

[skip ci]

[skip ci]

remove alias from postgres $__timeGroup macro

add $__timeGroupAlias macro to all sql datasources