cloud storage on Android

[Dirk Hohndel]

Thanks to Sebastian our mobile UI is making quick progress!
I fixed a couple more bugs that were introduced in the code restructuring
and now Subsurface-mobile almost sorta works again :-)

The exception is cloud storage. Thanks to a 10" tablet in landscape mode I
have a nice complete error message:

git clone of <cloud URL> failed (Failed to set permissions on file
'/storage/emulated/0/cloudstorage/<HASH>/.git/objects/pack/<packfile name>:
Operation not permitted)

The parts in <...> have reasonable content, just removed here for clarity.

I think Lubomir posted about the fact that we may be using the wrong path
on Android. I'll play with this later but wanted to send this out now in
case it rings a bell for someone.

/D