Bug 906324

Bug 906324

First cut at adding single-agent ICE test app (C++) 
and Python test wrapper.

-- Moved existing mtransport/test/ unit test code into
   mtransport/test/unit/ dir

-- Created new mtransport/test/apps dir for new files
   (suggest better place?)

-- I'm hoping to refactor the IceTestPeer class and share
   it between the new ice_peer and also ice_unittest 

-- The STUN and TURN options have not been exercised yet

-- The offerer/answerer option is not used (except for
   passing it to the NrIceCtx ctor, which doesn't use it)

-- The new test_ice_peer.py script gets copied to the
   mtransport/test/apps/ directory.  (suggest better 
   location?)  I run it from there.