Remove unnecessary runtime dependencies

* remove dependency on jquery-rails
* remove dependency on thor (appears unused).
* remove dependency on version (appears unused).
* remove rails 3.0 generators (gem already had a dependency on railties >= 3.2)
* remove Gemfile.lock (see [Yehuda's post](http://yehudakatz.com/2010/12/16/clarifying-the-roles-of-the-gemspec-and-gemfile/)).