support regex syntax in except_method checks

Hi. I found the except_method syntax didn't give me enough power to specify blocks of classes based on a name suffix, e.g. excluding all methods from the "unused method" check if their name ended with ```Responder```. It seemed this matching logic was a natural fit for regular expressions, so I've implemented that in the Excepted module. It still supports the original ```*``` wildcard character, so ```*#*``` will match all methods on all classes. But now you can also do ```.*Responder#foo_.*```.

Specs are included. What do you think?