Migrated StartManagingCursor to LoaderManager/CursorLoaders

This is a (first) try at migrating to LoaderManager. It seems to work properly on every device I tested it on. The code might need some more organizing. Maybe move some inner classes to their own files etc. I can do that some other day. 

Also I joined the note_edit.xml and note_edit_image.xml layouts to one to reduce code and for easier management.