Added listeners to be able to catch OnClick and OnFocusChange events

Hi there,

This is the first time that I do this, so I'm not pretty sure what I should write here... The thing is that I took your code to use it in a form, but also I needed that EditText was be able to react to onClick events and to onFocusChange events, so I added them through interfaces to not break encapsulation.

I hope you'll like it.
Cheers.