Expand this a bit to help eliminate issues later ... I'm assuming this works in the same way that a gemspec does.  Basically do the major and minor versions.

    spec.add_development_dependency 'bundler', '~> 1.5', '>= 1.5.3'
    spec.add_development_dependency 'rake', '~> 10.3', '>= 10.3.1'
    spec.add_development_dependency 'rspec', '~> 2.14', '>= 2.14.1'
    spec.add_development_dependency 'rubocop', '~> 0.21', '>= 0.21.0'
    spec.add_development_dependency 'simplecov', '~> 0.8', '>= 0.8.2'
    spec.add_development_dependency 'coveralls', '~> 0.7', '>= 0.7.0'
    spec.add_development_dependency 'travis', '~> 1.6', '>= 1.6.10'
    spec.add_development_dependency 'codeclimate-test-reporter',