pin the gemspec to a newer rspec version that is compatible with mocha > 0.12.8

  * see https://github.com/freerange/mocha/issues/130

  * without this fix rspec tries to use mocha/object which was removed from mocha
Merge pull request #1 from logicminds/rspec-fix

pin the gemspec to a newer rspec version that is compatible with mocha >...