@ashfurrow => RACify the keypad view

Keypad input sends is a stream man.
The bid view controller subscribes and passes sends the input to a textfield.

RAC Tests well using Dependency Injection, good advice on that. The technique is just changing the RAC stream that fakes the  keypad input triggers so that in tests it's runtimeable. Cool. :+1: 
It'd be super-cool to have this as derived state using the ReactiveCocoa binding mechanism replacement described [here](http://napora.org/a-swift-reaction/). I'll merge as-is and deal with it tomorrow.