fix and consolidate button class (color) logic

this has a companion PR in the service side: https://github.com/mozilla/treeherder-service/pull/84
The service PR returns the correct ``result_types`` for ``pending`` and ``running``.  Without that chance, the hide/show jobs button will show black for pending and running.

This now uses the same logic to get the button class and icon for job buttons as well as the hide/show job button and places that in a provider.

Also, fixed a few areas where I was returning the wrong color.