Do not restart vpn processes for every router update

Presently all the vpn processes are restarted when any
router is updated, even if the updated router do not
host any vpn services. 'device_drivers.ipsec.sync()'
updates all the vpn services which results in stopping
and then starting of the vpn processes.
This patch addresses the issue by
1. Passing router id information to the vpnservice_updated
2. (Re)starting the vpn process only if the
      - the vpn service is newly added or
      - the agent has been restarted before the sync or
      - the sync has the router id of the vpn service

Change-Id: I12825bc071033109bdcb93c89daa32012a8babb6
Closes-bug: #1393589
Merge "Do not restart vpn processes for every router update"