Add support for key('ctrl', ...) etc.

[zealotrunner]

key('ctrl',function(){}) not work, the same as alt, shift, command...
Is it by design?

It will be very useful in some cases.

[Daiz]

I also ran into this issue while trying to bind something to a shift press (key('shift, pageup' function(){})) and wondering why it didn't work until I hit 's' and the function suddenly fired.

[ansonkao]

Hi guys, I ran into the same problem and made a pull request visible over at Issue #136, take a look!