The Switch Event thread is the thread that processes events coming from all switches.
Right now its very fragile as an unhandled exception can cause the thread to die causing
the controller to be unusable. Making the thread more tolerant of exceptions and making
the shutdown of the thread more deterministic.

Change-Id: I31c31f012229de8e124c0c13fa651513daaf6776
Signed-off-by: Asad Ahmed <asaahmed@cisco.com>
Merge "The Switch Event thread is the thread that processes events coming from all switches. Right now its very fragile as an unhandled exception can cause the thread to die causing the controller to be unusable. Making the thread more tolerant of exceptions and making the shutdown of the thread more deterministic."