Handle SSH urls better and avoid race conditions when setting git local configs

[twillard]

Hi! This is a simple pull request fixing a couple issues I had locally when using this tool.

1. The SSH urls from github and elsewhere (ie. [email protected]:project/path/thing.git) weren't handled well by urllib without an explicit ssh:// scheme on the front, so to handle this I simply check if the parse failed, tack on a ssh:// and try again.

2. I got race conditions trying to set username and email without adding the git_process.wait() to the get_config method.

[twillard]

This should address at least some of issue #31

[twillard]

And issue #37

[skaldarnar]

This worked perfect for me. Would be nice to have it merged (or forked by someone with more time for PRs).