Add a shadow to .top-nav.
Reduce padding for .top-nav.
Style checkboxes to improve UX.
Style form to group benchmarks by category.
Display checkboxes as a column.
Titleize category name.

* We may get nil results if the benchmark file name has no underscore.
Increase columns used for body.
Make top navigation bar fixed.
Create an APIController.
Implement HTTP basic authentication for API endpoints.
Exit jobs immediately on Heroku restart.

See https://github.com/collectiveidea/delayed_job/commit/90579c3047099b6a58595d4025ab0f4b7f0aa67a
Add API environment variables when executing benchmark commands.
Update to Rails 4.2.