The LOMainActivity now needs to be aware of Document Providers, so we
pass the providerId and documentUri in the Intent so it can rebuild
the DocumentProvider and the IFile objects.

We also implement the ownCloud save operation.

TODO: since the local save operation does not have a callback, we do
not know when the cloud save operation should be performed. Now we
just wait 5 seconds to trigger it.

Change-Id: I060969e12888eca07c8c56ddc82cbed6c45a0739