Manage IP addresses

[nymous]

Currently we generate IP addresses in the 172.30.128.0/17 range during DB migration, hardcoded from a seed.

This is a bad idea, IPs are hardcoded (and we changed the network addresses), and creating that many addresses during initialization without asking is a bit bad ^^'

Create an IP address management interface, where we can see which IP addresses exist, how any are used/free, and create new network ranges.