Modify the code to:
* share assets and global settings wherever possible
* update links going both directions
* other small UI tweaks for uniformity with Treeherder
* Fixed a few routing dead-ends on the react side
* Removed the dead TestDetail file we weren't using anyway
* fix production domain urls
This moves the Sheriff panel out to a full-page app. The functionality
is basically the same, however. Much of the logic and HTML were just
copied from the Sheriff panel.
This also introduces ReactJS to the repo. This was used to speed up
the rendering of the reference data lists in the Exclusions detail
editor. The ``reactselect`` component is defined as normal JavaScript.
We decided not to introduce using JSX at this time.