For now, this uses a static list of sensors, which we can update occasionally.
This is mostly because OpenTSDB only supports pulling 25 sensors at a time from
its API (the /suggest URL). To be able to get all of them will require patching
Also note the patch to Bootstrap's typeahead support. This allows showing the
hints when no characters have been typed yet.
Remove extra bootstrap import
Add correct input type to sensor input
Add metric name typeahead hints to the sensor input.
Note that this commit requires patching bootstrap Typeahead to support
showing the typeahead when no text has been entered yet.