(QENG-104) Remove gems that were pinned for Ruby 1.8

We no longer use ruby 1.8 internally. There is no reason to keep it
around any longer.

![nuke the entire site from orbit](http://iruntheinternet.com/lulzdump/images/gifs/alien-sigourneyweaver-nuke-riley-orbit-1348491814r.gif)
@justinstoller I don't understand how this change would impact running your unit tests on 1.8.7 (e.g. `bundle exec rake spec`)