elasticsearch: do not set a placeholder to index name, if it's already specified

[skip ci]

[skip ci]

[skip ci]

Fix switching from es raw document metric breaks query editor

Explore: Fix table pagination styles

Explore: Dont set datasource in state if navigated away

fixed singlestat guage ceneterd dot rendering issue

Upgrades the go-macaroon package

- get rid of drop shadow
- get rid of top border
- add min height for better no-data placement
- add margins

Restore user profile preferences

[skip ci]

Clarify wording of playlist protip

Per discussion on https://github.com/grafana/grafana/commit/154fbe2413f9abe33157baa563e42fbf67e2f27b#r31238888 it seemed like this wording might be easier to understand.

Datasource selection triggers a connection test, on success
the DS is set in the Explore state. If the test takes long and user
selects a different DS, and just after that the first test succeeds,
then the first DS overwrites the state.

* when test returns check if datasource is still the requested one

React Gauge Panel - first step

Fix gofmt issues

See,
$ gometalinter --disable-all --enable=gofmt --deadline 10m --vendor ./...
build.go:1::warning: file is not gofmted with -s (gofmt)
scripts/build/release_publisher/externalrelease.go:1::warning: file is not gofmted with -s (gofmt)
scripts/build/release_publisher/localrelease.go:1::warning: file is not gofmted with -s (gofmt)
scripts/build/release_publisher/main.go:1::warning: file is not gofmted with -s (gofmt)
scripts/build/release_publisher/publisher_test.go:1::warning: file is not gofmted with -s (gofmt)

Remove Origin and Referer while proxying requests

[Bugfix] Don't drop the value when it's equal to None

Fix last megacheck issues

See, https://github.com/dominikh/go-tools/tree/master/cmd/megacheck