tests: refactor vpp_object.py

Move __str__ to super for all subclasses of VppObject
Implement __repr__ in VppObject
Implement __hash__ and __eq__

Change-Id: Ibd4ea37b84b17f499ab86630fb5b9ed9c8b4b1c2
Signed-off-by: Paul Vinciguerra <pvinci@vinciconsulting.com>

test/vpp_mpls_tunnel_interface.py

@@ -60,9 +60,6 @@ class VppMPLSTunnelInterface(VppInterface):
                 return True
         return False
 
-    def __str__(self):
-        return self.object_id()
-
     def object_id(self):
         return ("mpls-tunnel%d-%d" % (self.tunnel_index,
                                       self.sw_if_index))