Add contrib feature to setup.py so we can have it on PyPI
Add contrib feature to setup.py so we can have it on PyPI

cklein/wtforms,Aaron1992/wtforms,jmagnusson/wtforms,Xender/wtforms,Aaron1992/wtforms,subyraman/wtforms,wtforms/wtforms,pawl/wtforms,pawl/wtforms,crast/wtforms,skytreader/wtforms,hsum/wtforms