This change includes:
- (on possibly older python versions ?) a string variable test using the 'is' operator fails (so it always return ok immediately after initial delay)
- add a missing socket.settimeout() for the state=started case (if the machine does not exist, timeout defaults to 60 seconds)
- add a connect_timeout option to customize the default connection timeout
- use socket.shutdown(2) to close immediately
- return the elapsed time
This takes started, stopped and restarted.
Started returns when connecting is possible.
Stopped when connecting is not possible.
Restarted first waits for connecting to be impossible and returns when it is
possible again.
