move to PTK prefix. 3 letter prefix > 2 letter prefix.
rename everything to use 3-letter PTK prefix
finish renaming things
Call super in resignFirstResponder
Merge pull request #51 from jlmendezbonini/call_super

Call super in resignFirstResponder
Update README.md
Merge remote-tracking branch 'stripe/master'

Conflicts:
	PaymentKit.podspec
	PaymentKit/PKView.h
	PaymentKit/PTKView.m
new tag