Feature/friendlist

NEW:
* context menu for friendlist:
![image](https://cloud.githubusercontent.com/assets/1217999/4800811/1d80788a-5e2a-11e4-8aa1-8db8dc072403.png)


TODO:
* symbol if player is in lobby, host, ingame (where can i grab the data? channl.py#updateChatters?)

FUTURE:
* We must add more api-methods, signals, slots, e.g. for all commands for the context menu
 (currently duplicated code)