Usability: auto-find ssh identify & add option to change default network port.

@brthor asked me to post this issue.  I don't have time to work on a PR through.

This is a promising utility. I had to work through a) no py3 support #14, b) ssh identify file must be specified though mine is in default location, and c) port 5000 is already in use on my servers and there is no option to change to another port.