pgw does not setup IP/link/NAT when it comes online

[spencersevilla]

When the PGW launches, it brings up a virtual interface ogstun. It does not do anything else to this interface (e.g. bring the interface up, assign it an IP address, setup NAT, etc).
I wrote a script to do all this and configured it to run every time the PGW comes online, but this solution feels dumb/janky.

At a minimum, the NextEPC pgw should definitely assign the interface an IP address and bring it up. NAT is more controversial because (1) not everyone wants to run NAT, (2) not everyone wants to forward/route Internet bound traffic, and (3) we'd have to know the name of the outbound/upstream interface (e.g. "wlan0").

We can brainstorm better solutions for NAT, but we should definitely fix the pgw.