I followed this developers notes on how to test multiple versions of Rails.
http://schneems.com/post/50991826838/testing-against-multiple-rails-versions

He recommended putting the dependencies in the Gemfile and then building the gemspec using Jewler.  I didn't add Jewler to hydra-role-management to dynamically create the gemspec using the current version of Rails because I found that defeated the purpose of my code.

One of the problems I had starting out was that the original gemspec did not versions on dependencies.  If a developer is going to use Rails 4, the gemspec would require different versions than if the developer would use Rails 3.  How to marry those two needs seemed overly complicated so I relied upon this Gemfile to resolve some of those issues.