Delete only the link between vrouter and VM during vrouter failure

Change-Id: I691932ec129b9918eb25da4fc63d7b31a56aede8
Fix the cleaning of EVPN tor NH.
Also set the subnet flag in path of subnet route. This path is where discard NH is added i.e. local peer

https://bugs.launchpad.net/juniperopenstack/+bug/1372780

Change-Id: If84b6f5cd133d6e4aee5dfbeab780e897a0e8e4f
Merge "Delete only the link between vrouter and VM during vrouter failure"
Merge "Fix the cleaning of EVPN tor NH. Also set the subnet flag in path of subnet route. This path is where discard NH is added i.e. local peer"