Make VDM Demo connectivity more robust

 - Add socket timeout to recover if the network is lost during
   the accept() call
 - Only start the sessions once
 - Keep the discovery session alive
 - Remove redundant locks and boolean switches

Bug: n/a
Test: manual
Change-Id: I793a95bc8e16a2688f35c8c552a63055b545b6c0
4 files changed