Does not recognize custom key prefix

[cfiske]

The current RegExp for matching keys only matches the prefix of an original key (cccccc). If you set a custom key that prefix changes to vvcccc (and kkjjjj for Dvorak) and is not recognized.

I think it should be as simple as adjusting the prefix part of the respective RegExp to (cc|vv)cccc and (jj|kk)jjjj but I am not much of a JavaScript/CoffeeScript guy.