Generalize memberbooth so others can use it easier

[BerglundDaniel]

See related makeradmin issue

I guess the main work would be to change some texts etc? @emanuelen5

[emanuelen5]

1. Support multiple languages #121 might be a good start.
2. Improve documentation / test how easy it is to install from scratch
3. Make it configurable what type of labels that can be printed. Either just by removing some buttons, or making it modular.

I mean, lots of things could be done.

It's a lot easier to define this task when there is actually someone who wants to start use the memberbooth for their own Makeradmin instance. So I think it makes sense to wait with this issue until that day comes.