Small cleanup, also a "maybe" solution to the enum problem you seemed to face.

- removed the reference to the file VerbalExpressionsEnum, which
  was gone anyways
- added a sealed class for collecting predefined enums that is
  a bit more usable then an enum.
- refactored the given class and tests to use the new CommonRegex
  class.

Note:  Unfortunately VS2012 was a bit harsh with the formatting, sorry! Try the "ignore whitespace" when you review this with your favorite tool.