Add an OpenTSDB datasource.

This adds support for querying OpenTSDB for metric data.
Proof of concept of multiple groups using "host"

Initial test to make sure this plan works using a predefined alternate
group by. Now to actually figure this out based on the query and add
some UI for it.
Parse additional group by columns from a raw query

This needs some further polishing but now parse out additional group by
columns from a raw query, although it really only supports one
additional column.
Fix single line naming
Hookup additional group by into UI

Allow additional group by fields to be specified without writing a full
on influx query by hand.
Fix typos in condition names
Cleanup the influx query parsing
Add tooltip messages to icons in query editor.
Cleanup from jshint
Check for negative return
Don't retry on http status codes >= 300

These status codes are likely to be to be unretryable errors coming from
influx (most likely bad queries)
Merge branch 'master' into add-influx-group-by

Conflicts:
	.gitignore
	src/app/partials/influxdb/editor.html
	src/app/services/influxdb/influxdbDatasource.js
Formatting.
removed unused code
small fix to config.sample.js
fix for build step that replaces @grafanaVersion@ with correct version string
elasticsearch saving does now work, still have to do ttl and temp dashboard
fixed default dashboard json editable flag, accidentally set to to false
removed dependence on elasticsearch js client from search, will try to remove this depdence in other places and just use $http, elasticsearch js client is to big and does not provide enough value
more work on refactoring ES usage