revert font-awesome-rails to 4.0.3.1, added oink gem for memory usage logging

- set font-awesome-rails to 4.0.3.1 because that’s what the app is
using and I got an error running bundle install because it was
specified as 4.0.3.2 in the Gemfile (“bundle is locked at 4.0.3.1”
- added oink gem to help trace possible memory leaks