VRouter NetNS script fix

- Set a display name on veth
- Use a default ID as rt table in the netns
- Correct the scons script to support dependance on the vrouter API
  library and run unit tests

Change-Id: If7e42147849dade6fd6f6aa56a1bc6a829441d53
Signed-off-by: Édouard Thuleau <edouard.thuleau@cloudwatt.com>
Merge "VRouter NetNS script fix"