Add a timeout for the socket connection

[rjwills28]

This PR addresses the issue described in #36 where the method to connect to a socket can block for ~ 2 minutes. Instead, I have added a timeout for the connection, which is configurable in the properties. A default of 5 seconds has been used for the timeout if not specified.

[kasemir]

Looks good to me: No change unless one reduces the now-configurable connection timeout

[rjwills28]

@kasemir thanks for taking a look at this. I set the configurable connection timeout back to 2 minutes to resemble the original behaviour of the open() method (which took ~2 mins to timeout). If you don't think this is necessary then I can reduce it?

[kasemir]

I set the configurable connection timeout back to 2 minutes

I'd say the default can be shorter.
Of course unclear what a good default is.
Should the TCP connection succeed in ~1 second?
I think the command line "caget" has a 1 second default.