Add creator and online information to group member list

![device-2016-12-06-102258](/uploads/90e19a6ca31aaf91c6ebf3ea8e218b3f/device-2016-12-06-102258.png)
![device-2016-12-06-110113](/uploads/3fd62f7cdfe75419a07262356d27b952/device-2016-12-06-110113.png)

Closes #813

See merge request !448