Fix #80 Update rubocop gem
Convert specs to RSpec 3.0.2 syntax with Transpec

This conversion is done by Transpec 2.3.1 with the following command:
    transpec

* 2 conversions
    from: Klass.any_instance.stub(:message)
      to: allow_any_instance_of(Klass).to receive(:message)

For more details: https://github.com/yujinakayama/transpec#supported-conversions
Merge pull request #81 from jhx/issue_80_update_rubocop_gem

Fix #80 Update rubocop gem