(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 You should probably put beaker into a special section of your Gemfile, and then do a `--without` when running specs.

At this point I actually can't run beaker with any recent selenium/capybara gems in the same Gemfile - they now require gems that we explicitly filter out (newer nokogiri and mime-types). Either we get this in here, or I have to add it to the internal beaker and that'd make me a sad :panda_face: