Fix broken test for Python 2.x

Fun fact: for Python 3.x you don't need to explicitly implement __ne__
method if __eq__ exists, but you have do this for 2.x or your objects
may be equal and non-equal at the same time. Seems like, before
refactoring, operator.eq had used right logic.

Author: kxepal

jsonpatch.py

@@ -248,6 +248,9 @@ def __eq__(self, other):
                 return False
         return True
 
+    def __ne__(self, other):
+        return not(self == other)
+
     @classmethod
     def from_string(cls, patch_str):
         """Creates JsonPatch instance from string source.
@@ -391,6 +394,9 @@ def __eq__(self, other):
             return False
         return self.operation == other.operation
 
+    def __ne__(self, other):
+        return not(self == other)
+
 
 class RemoveOperation(PatchOperation):
     """Removes an object property or an array element."""