Don't block the UI when rearranging icons.

The pause is mostly notable when a sync is happening at the same time.

The related function addItemToDatabase() is unchanged by this CL
though as it populates item.id and would need more invasive changes
elsewhere.

Change-Id: I6538445aeb15d9efedf99f262c39f6175f7f1e0e
1 file changed