Fix l2 pop doesn't propagate ip address updates

Propagates ip address changes when an ip address is :
added, removed, or changed.
Add a new rpc call for the updates of forwarding informations.

Fixes: Bug #1234137
Change-Id: Ib5b971bd02f20a0ea73f88ce9685e944226bb5a2
(cherry picked from commit e6a368a697e936f40a0882b236b2be17e1520436)