Change IMAP IDLE to use TPL Tasks - no more abort and allows user to catch socket exceptions. Add an exception event so users can catch exceptions that happen in the tasks.  Removed call to NOOP after IDLE timeout.  Add server and idle timeout properties. Change Disconnect to close _Stream.
Thread/Task/Resource cleanup in Disconnect
Merge pull request #155 from philipspigelmire/master

IMAP IDLE changes