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)
changed default row height to 250px
Row editing and adding new panel is now a lot quicker and easier with the new row menu (Issue #475)
Merge branch 'master' into add-influx-group-by

Conflicts:
	.gitignore
	src/app/partials/influxdb/editor.html
	src/app/services/influxdb/influxdbDatasource.js
Formatting.
Cleanup of config.sample.js, removed graphiteUrl setting, it will still work for next release
Format seconds metric by week if needed
Adding JSCS (javascript style checker)
Merge pull request #476 from lyrixx/axis-s-week

Format seconds metric by week if needed
update changelog