[Owncloud] App settings

[Jan-Christoph Borchardt]

By the way, Brice (eMerzh) and I played around with a new settings
interface and implemented it in the Bookmarks app:
https://github.com/owncloud/apps/issues/51

Now we should move that out of the bookmarks app into core, to have it
as a general style for all apps. We want to move from the speech
bubble popovers to this integrated sliding. It will look even better
with the new navigation branch where the global settings are not in
the bottom right anymore.