Add an OpenTSDB datasource.

This adds support for querying OpenTSDB for metric data.
InfluxDB Filters: added function to generate filter list.
InfluxDB Filters: added filter to queries.
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 'feature/influxdb-filters' of github.com:mavimo/grafana into mavimo-feature/influxdb-filters
Fixing PR for influxdb filters
added a little padding for metric target editor rows, making tthem sligly heigher
Merge branch 'master' of github.com:grafana/grafana
Merge branch 'master' into mavimo-feature/influxdb-filters
Improvement to InfluxDB query editor and function/value column selection, more space efficient, Closes #473
Fix for exclusive series toggling (hold down CTRL, SHIFT or META key) and left click a series for exclusive toggling
  CTRL does not work on MAC OSX but SHIFT or META should (depending on browser) (Closes #350, Fixes #472)