VPP-1508 Python3 abstract classes

Update the syntax to support abstract classes in python 2 and python 3.

Depends on: new style classes -- https://gerrit.fd.io/r/16166

Change-Id: Iad2c1240149f38b3faca1b37ab95d3d210e1daee
Signed-off-by: Paul Vinciguerra <pvinci@vinciconsulting.com>

test/test_lisp.py

@@ -1,4 +1,7 @@
 #!/usr/bin/env python
+
+import abc
+import six
 import unittest
 
 from scapy.fields import BitField, ByteField, FlagsField, IntField
@@ -28,6 +31,7 @@ bind_layers(LISP_GPE_Header, IPv6, next_proto=2)
 bind_layers(LISP_GPE_Header, Ether, next_proto=3)
 
 
+@six.add_metaclass(abc.ABCMeta)
 class Driver(object):
 
     config_order = ['locator-sets',
@@ -61,7 +65,7 @@ class Driver(object):
                   Raw(payload))
         return packet
 
-    @abstractmethod
+    @abc.abstractmethod
     def run(self):
         """ testing procedure """
         pass