Add support for minitest-focus

Add "focus" above a test to make minitest just run that test.
Create the /status endpoint.

Return whether or not the app is okay, the stats of redis, the status of
sidekiq, and how many sidekiq jobs there are.
Use sinatra reloader in development.

Yay reloads!
Document the /status endpoint.
Merge pull request #3 from opscode/status_endpoint

Create the /status endpoint