Update ruby and gem dependencies

I wasn't sure how best to break up the changes included here but since it affects Gemfile and Gemfile.lock all around figured it was best as one pull request since multiple ones would require pull requests being done in a certain order. If you prefer I break it up let me know.

* Updates to latest Ruby version 2.1.1
* Bundle update all gems to latest version (no issues)
* Use your rack-standards gem instead of inline standards class in lib
* Use your sprockets-memcache-store gem instead of inline cache class in lib