[#106] Address new url.Parse behavior during setup

[awoodbeck]

These changes should address the new url.Parse behavior. The relative SSH URL portion is treated as a port. Since ports parsed by url.Parse must now be numeric, this breaks relative SSH URLs.

The approach I took was to inject a temporary port number, parse the URL, and remove the injected port. All tests pass. That being said, this code needs more eyes on it to make sure all edge cases are addressed by these changes.

[ricardoboss]

Does this fix #106?

[awoodbeck]

Does this fix #106?

It resolves the issue for me and is the most minimal approach I could come up with to address the issue. There's no telling when the author may rule on this PR, so feel free to use the master branch in my fork until then. My master branch is diverged from this repo only insofar as the import paths are concerned and to include my changes in this PR.