Re-enable writable filesystem federation

* Fixes https://www.pivotaltracker.com/story/show/70954532
* Depends on https://issues.jboss.org/browse/MODE-2252
Why is this test ignored? 
A comment including a new ticket URL indicating the issue would be helpful in circling back on this later.

...actually, since we are no longer writing properties to disk, the test should probably just be removed.