Use descriptive method names instead of color methods

Color methods are deprecated and will be removed in RSpec 3.0. See:
https://github.com/rspec/rspec-core/commit/5bf26bc056747ad356889f22ed8d3bb2c3c2f692
Make rspec >= 2.13 a runtime dependency
Merge pull request #42 from sferik/colors

Use descriptive method names instead of color methods