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.
Improvement and polish to the OpenTSDB query editor (Issue #492)
Merge branch 'master' of github.com:grafana/grafana
removed commented out sections of the opentsdb datasource
Refactoring and rewrite parts of influxdb group by feature from PR #441
Graphite query lexer change, can now handle regex parameters for aliasSub function (Fixes #126)
changed version to 1.6.0
updated karma dependencies in package.json