fixed folder discovery

at least for egroupware. Was broken before for every server.

Open-WebOS-DCO-1.0-ned-off-by: Achim Königs <garfonso@tratschtante.de>
fixed collection sync

local collections were never deleted. Now they are deleted and
we delete all objects from local db.
During upsync we will check if a local collection still exists
for the object, to prevent deletion of objects on the server for
the objects from the locally deleted collection.

Open-WebOS-DCO-1.0-ned-off-by: Achim Königs <garfonso@tratschtante.de>
added per collection index for contacts

this is necessary for deleting all elements of a collection when
the collection is deleted. Yes, the collectionId is called
calendarId here. This is webOS fault..

Open-WebOS-DCO-1.0-ned-off-by: Achim Königs <garfonso@tratschtante.de>
disabled postPutRemoteModify

this is because a webOS patch called "sync-fix-for-stable-upload"
will run webOs into a endless loop, consuming all battery and
a lot of system ressources. THIS IS BAD. We need to fix the patch.
Or we need to get rid of the patch. Or we just keep this disabled.
The downside of disabling postPutRemoteModify is that local changes
will first be transmitted to the server and then be downloaded again
from the server unnecessarily, because local etag does not get updated.

Open-WebOS-DCO-1.0-ned-off-by: Achim Königs <garfonso@tratschtante.de>