Fix folder deletion; support folder rename (#2118439) DO NOT MERGE

* Folder delete had a subtle error that could cause subsequent folder
  changes in the same sync to fail (using wrong end tag)
* Folder change (rename, move) wasn't implemented; this was added and
  tested.  The change is very straightforward and low risk.

Change-Id: I9733dc5da1a535c388e2feb299a641642ba531c2
1 file changed