AFK room for free servers

From a feedback suggestion:

> Ability to create sub servers [channel] would be very much appreciated. (for things like when people need to afk but they dont want to mute themselves or turn off mumble) this is purley an addition of convenience

Seems like a reasonable request. We would need to build in support for creating channels via https://github.com/alfg/murmur-rest API first, before implementing within Guildbit.

Looking for contributors!