Updated gem dependencies.
Convert specs to RSpec 3.0.0 syntax with Transpec

This conversion is done by Transpec 2.2.1 with the following command:
    transpec

* 5 conversions
    from: be_true
      to: be_truthy

* 1 conversion
    from: be_false
      to: be_falsey

For more details: https://github.com/yujinakayama/transpec#supported-conversions