[RFC] cygport upload

[Andrew Schulman]

> I have created an upload branch in cygport git based on master with
> Andrew's upload work for further testing.

FWIW, I've been using it to upload my packages since the last update on Jan. 17,
and before that too, with no problems.

I always keep my ssh keys loaded in a running ssh-agent, so I've tested that
case pretty well.  I think it would be most useful to test the other cases:
ssh-agent running but key not loaded; ssh-agent not running; private keys
encrypted/unencrypted.

Andrew