Network must be created with working ml2 driver

In getting the network attachment/detachment working on the Cisco 300 series, I noticed that the port could only be bound after the network was created... when there is a working ml2 driver. It makes sense to attempt to always assert that the vlan is present on the switch, because what if the configuration is lost, or accidentally reverted?

I think the easiest thing would be to do this as part of the port plug, but I also feel like that is kind of a hack.