nvp:log only in rm router iface if port not found

The code currently raises when it's not able to find the port to be
deleted on the backend. This might happen, for instance, when the
port is manually removed or, in some cases, if port creation failed
in the first place.

There's little sense in raising when a resource to be removed is not
found; therefore this patch replaces the raise statement with a log
statement.

Bug 1240720

Change-Id: Ifa756b07ef41346a44325341c8e0e8994dc64dde
Detect and process live-migration in Cisco plugin

With Cisco/Nexus plugin, migration is not fully supported. Logic to detect
port binding change needs to be added in update_port(), and provisioning of
nexus switch(es) should be done accordingly

added test code for update_port() in the model layer and the db layer

Closes-Bug: #1229217

Change-Id: I2bd76030711c9d15462e91da9e4c0836a424834f
Merge "nvp:log only in rm router iface if port not found"