Add back `require 'guise/version'`
Use `String#constantize`
`class_attribute` already provides an instance reader
Switch to 1.9 hash syntax
Convert specs to RSpec 2.14.7 syntax with Transpec

This conversion is done by Transpec 1.7.0 with the following command:
    transpec

* 16 conversions
    from: obj.should
      to: expect(obj).to

* 9 conversions
    from: obj.should_not
      to: expect(obj).not_to
Include activesupport in Appraisals
Add named scopes for guises on association
Remove 1-letter variable names