Text field delegate methods

[jchaager]

Added in logic to invoke the FKTextFieldDelegate methods for:

textFieldShouldBeginEditing:
textFieldDidBeginEditing:
textFieldShouldEndEditing: 
textFieldDidEndEditing: 

The remaining Delegate methods are not yet implemented.

[jchaager]

There was a stray code change in the [FKTokenField layoutSubviews] method. Removed it to keep the pull request clean.