Issue with localhost face cleanup in NDNController

[almgong]

So, the problem is we need to destroy the localhost face used to communicate with the NFD. However, we need a localhost face in order to explicitly destroy all of the peer faces from previous WD sessions.

[almgong]

One idea: always keep this face alive. Simply unregister the localhop prefix (which is the only prefix ever registered to it) on cleanUp().

[almgong]

Another way, we can instantiate a new localhost face for NFD communication JUST for cleanUp(), and continue to destroy the one created during normal operation

[almgong]

We used the above solution (create a new localhost face), with expected results.