Update notes for submitted changes

* Agent UVE changes (1) While polling interface stats from Vrouter, fetch the stats in back to back requests instead of sending request for next set of interfaces in next 30 second timer interval. Send UVE (related to stats) only after the results from all the interfaces are obtained (2) Also after obtaining vrf stats from Vrouter, only send VrfStats (if changed) in VN UVE. No need to evaluate other fields of VN uve for change. (3) Add UT for the changes Change-Id: Id94c85154dccac7db951444e7a2f40513c5d6b43