Add IRB test

- JIRA: CSIT-255
- create loopback interfaces
- move pg-interface specific arp and neighbor discovery from vpp_interface to vpp_pg_interface
- base configuration of IRB tests
- IP test scenario

Change-Id: I9945a188163652a4e22325877aef008c4d029557
Signed-off-by: Matej Klotton <mklotton@cisco.com>

test/util.py

@@ -1,8 +1,7 @@
-from logging import *
+import socket
 
-
-class TestHost(object):
-    """ Generic test host "connected" to VPP. """
+class Host(object):
+    """ Generic test host "connected" to VPPs interface. """
 
     @property
     def mac(self):
@@ -14,6 +13,11 @@ class TestHost(object):
         """ IPv4 address """
         return self._ip4
 
+    @property
+    def ip4n(self):
+        """ IPv4 address """
+        return socket.inet_pton(socket.AF_INET, self._ip4)
+
     @property
     def ip6(self):
         """ IPv6 address """