Optimizations to improve flow setup rate
- Fetch UTCtimestamp only at the beigning of flow_handler proto process
  i.e., max upto 32 entries can have same setup time.
- get ksync nexthop from DB state instead of lookup
- Synchronous KSync-Vrouter operations, to remove limitation of 200
  outstanding message (for faster processing.)
Need to consider multiple response to one request.
Taking care of review comments.
    - added a knob in KSyncSock to run as Sync or Async
    - reverted changes for UTCtimestamp, will take it up later.
For link local service request, do src port nat. Bind to a local port, and use it as nat src port.
Update test case
Merge remote branch 'upstream/master'
Update for code review
Merge remote branch 'upstream/master'

Conflicts:
	src/vnsw/agent/pkt/flow_table.h
	src/vnsw/agent/pkt/test/test_pkt_flow.cc
Merge remote branch 'upstream/master'
Merge remote-tracking branch 'upstream/master'
fixing test cases for ksync running in sync mode.
adding test-case to simulate failure for get nh from DB state
Fix for label mismatch in the path programmed by local peer and remote peer for l2 route
Fix for vnswad core: If multicast object is present in delete state and peer goes down then no rebake is to be done for comp NH
Fix for multicast crash: Rebake comp NH when peer goes down only if multicast object is not deleted
Update multicast.cc
Update multicast.cc
Adding test case for KSync running in async mode.
Merge pull request #342 from Juniper/ashoksr_ut

UT for Agent UVE introspect commands
Handle a couple of cases/exceptions when service have gone away
UT for db_handler.cc