Upgraded jquery-rails from 2.1.4 to 3.0.0 and removed minitest gem

Upgraded jquery-rails from 2.1.4 to 3.0.0 by patching 2 lines in local jquery.quicksand.js file
(based on this article: https://github.com/razorjack/quicksand/issues/94).

* Then removed minitest gem since it was not needed.