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: Iacd368b64650bf7eabd342a236339d1711aea4cd

dracclient/resources/bios.py

@@ -278,6 +278,9 @@ class BIOSAttribute(object):
     def __eq__(self, other):
         return self.__dict__ == other.__dict__
 
+    def __ne__(self, other):
+        return not self.__eq__(other)
+
     @classmethod
     def parse(cls, namespace, bios_attr_xml):
         """Parses XML and creates BIOSAttribute object"""