Improve length and ranging validators
Add equal validator
Add equal validator unit test
Add regexp validator
Minor fix
Add regexp validator unit test
New validators
Missing import
Fix Python 3 compatibility
Add predicate validator
Add predicate validator unit test
Make Flake8 happy
Use basestring to allow regext to be a bytes object
Add acknowledgement
Merge branch 'philtay-dev' into dev

Conflicts:
	HISTORY.rst