add hash function to cqlengine.columns.Column
add hash function to cqlengine.columns.Column

restore hashability to Column in Python 3.x

PYTHON-618

thelastpickle/python-driver,mambocab/python-driver,datastax/python-driver,thelastpickle/python-driver,datastax/python-driver,stef1927/python-driver,vipjml/python-driver,coldeasy/python-driver,coldeasy/python-driver,stef1927/python-driver,mambocab/python-driver,vipjml/python-driver