Create Group for each application id

[newhinton]

This allows for a more fine grained controll over notifications.

todo:

• [x] Use Appname as Groupname, not id
• [x] Think about how to generate groups outside of onMessage()

Do we have a list of applications with their id's and names in the InitializationActivity? That way we can pregenerate all channels and groups.

Edit: I do not now how failsave it is to generate the list in the MessageActivity.onUpdateApps()-Method.