Starring

This adds the ability to add stars/notes to jobs.
This relies on the ``starring`` branch in treeherder-service to be merged first: https://github.com/mozilla/treeherder-service/pull/64

What's there:
* display all existing notes / stars on a job in the detail window
* add new notes
* keeps history of notes

What's not there (all assigned to tasks in tracker):
* the notes don't affect the result set / job view yet.
* star types aren't in the db yet.  they're hard-coded in a ``provider``.  But that provider can be setup to populate itself with the refdata values later.
* the drop-down for star types should show the color.  we'll need a more advanced ``select`` object like ``select2`` or ``bootstrap-select`` to do that.