Use route method in vnc_cfg_api_server.py so that there is a generic try/catch + log on any exception encountered in REST api handling.

Change-Id: I90fdd65aaeacbf0833dd586c3da7f31e90e9e71f
Speedup API server startup:
1. Accumulate ifmap config message during resync window and publish bulk messages. Every 1Mb of config is sent in one shot.
2. Maintain a cache of ifmap config and refer to it while updating the ifmap server.
3. While updating an entry, group the PublishUpdate messages and ensure only one update is sent.
4. Use async method to send message to ifmap.

Contrail-control changes are sent in https://review.opencontrail.org/#/c/907/

Code changes are from Pedro, Ajay and me.

Change-Id: I42227de8029e16a2c435bc3a2d4ea0d0529481b3
Fix a result code which is not handled

At some part the generator doesn't generate
the code to handle the not found result error.

Change-Id: Id4edd2f8b1fa8887e1d41ba72ee20a9073d4bb26
Merge "Speedup API server startup: 1. Accumulate ifmap config message during resync window and publish bulk messages. Every 1Mb of config is sent in one shot. 2. Maintain a cache of ifmap config and refer to it while updating the ifmap server. 3. While updating an entry, group the PublishUpdate messages and ensure only one update is sent. 4. Use async method to send message to ifmap."
readme file