Update UIControlEventEditingDidEndOnExit

EZFormInputControl should not be emulating UIControlEventEditingDidEndOnExit. After considering chrismiles/EZForm#17 resignFirstResponder would be better suited sending UIControlEventEditingDidEnd instead.

### Reasoning

When using the scrollView demo, EZFormInput control would would send ```- formFieldInputFinished:``` when tapping the next/previous buttons. The EZFormTextFields don't do this on next/previous they send ```- textFieldEditingDidEnd:```. ```- formFieldInputFinished:``` is only called after tapping a return key.