Fix handling of /31 and /127 assignments
Fix handling of /31 and /127 assignments

When one searched for available addresses in a /31, none would be
returned since we usually skipped handing out the network and broadcast
addresses. Since those are non-existent on a /31, we bypass the rules
somewhat.

Fixes #166

SpriteLink/NIPAP,plajjan/NIPAP,garberg/NIPAP,garberg/NIPAP,fredsod/NIPAP,SpriteLink/NIPAP,SoundGoof/NIPAP,plajjan/NIPAP,bbaja42/NIPAP,ettrig/NIPAP,bbaja42/NIPAP,fredsod/NIPAP,SoundGoof/NIPAP,plajjan/NIPAP,SpriteLink/NIPAP,SoundGoof/NIPAP,SoundGoof/NIPAP,bbaja42/NIPAP,SoundGoof/NIPAP,fredsod/NIPAP,fredsod/NIPAP,bbaja42/NIPAP,plajjan/NIPAP,ettrig/NIPAP,bbaja42/NIPAP,garberg/NIPAP,plajjan/NIPAP,garberg/NIPAP,SpriteLink/NIPAP,ettrig/NIPAP,bbaja42/NIPAP,garberg/NIPAP,plajjan/NIPAP,SpriteLink/NIPAP,SoundGoof/NIPAP,fredsod/NIPAP,fredsod/NIPAP,ettrig/NIPAP,ettrig/NIPAP,ettrig/NIPAP,SpriteLink/NIPAP,garberg/NIPAP