Increase default metadata_workers, backlog to 4096

While deployment tools might want to change the number of workers
to match the number of cores (Or some fraction of it), any default
other than 1 should be outright better.

Inspired from 19:34:
https://www.youtube.com/watch?v=AF9r_VQrcJ0

DocImpact
Closes-Bug: #1323005
Change-Id: Ie90000183ae67ff391a23ca3213fd23aef5f4dc5
Big Switch: Catch exceptions in watchdog thread

Catch and log exceptions in the watchdog greenthread to prevent
them from stopping the periodic consistency checks.

Closes-Bug: #1330135
Change-Id: I6834c0fee0429bb72b8c61307be7bdca77f6de9b
Control update, delete for cisco-network-profile

Add new behavior to control update and delete operations for the
cisco-network-profile resource extension.
The new behavior is to allow update and delete operations only if
there are no neutron networks associated with a particular
cisco-network-profile instance

Change-Id: I000a03c1ffd5c02e7b827ec757287633e5a5dd64
Closes-Bug: #1323867
Merge "Control update, delete for cisco-network-profile"
Merge "Big Switch: Catch exceptions in watchdog thread"
Merge "Increase default metadata_workers, backlog to 4096"