Add __ne__ built-in function
Add __ne__ built-in function

In Python 3 __ne__ by default delegates to __eq__ and inverts the
result, but in Python 2 they urge you to define __ne__ when you
define __eq__ for it to work properly [1].There are no implied
relationships among the comparison operators. The truth of x==y does
not imply that x!=y is false. Accordingly, when defining __eq__(),
one should also define __ne__() so that the operators will behave as
expected.
[1]https://docs.python.org/2/reference/datamodel.html#object.__ne__

Change-Id: I52d4b7396136dd3be7b8767dccb0613e8faba536

sapcc/python-monascaclient,stackforge/python-monascaclient,openstack/python-monascaclient,openstack/python-monascaclient,sapcc/python-monascaclient,stackforge/python-monascaclient