Fixed issues with Inventory augmentations being over-written (ExternalInterfaces...

Fixed issues with Inventory augmentations being over-written (ExternalInterfaces/Tunnel)

Externals
Neutron-ovsdb: InventoryHelper is writing these to CONF
SwitchManager is reading these from OfOverlayNodeConfig which comes from
CONF but it handles these inside a loop that is processing things from
FCNC.OPER.

Tunnels:
Neutron-ovsdb: InventoryHelper is writing these to OPER (which you never
see in POSTMAN… weird but squirrel).
SwitchManager handles these in two places: Looping on FCNC.OPER looking
for “*vxlan*", and processing OfOverlayNodeConfig from CONF.

Change-Id: I12a5738e3832228032368f0b5b45dcb050023a16
Signed-off-by: Keith Burns (alagalah) <alagalah@gmail.com>