Don't teardown things after sockets have been closed

Before, the call to closeAll() in McsService#connect() would trigger a SocketException (Socket closed) in McsOutputStream and/or McsInputStream. This would send a teardown message causing McsService to take the new connection down right away. In unlucky situations, this could cause small connect/teardown loops. This commit hopes to prevent those.

Change-Id: Id347d598e028bdd1ba2622cd6a5c6b07874335d6