Add more messaging functionality

[Lullebullelukas]

Basically make the group message tab look more like the web page. Make it possible to show all members of a groupchat. This concept was brought up during the "Bara SpindelMÄN?" event. Below is a picture of how one would navigate to show the group members.

[fnktiqaosofy]

This isn't passed to the user by the API.
I have a dummy page working though, so this can be finished quickly if the API-problem is solved (read: i can't fix the api thing by myself).