Summary:
See <https://github.com/facebook/phabricator/issues/467>. @dctrwatson also ran into an issue where we were trying to `setPass()` a GitURI.
- For Git and Mercurial, properly generate credential URIs where relevant.
- Don't try to `setPass()` on Git-style URIs.
This isn't perfect but should clean things up a bit.
Test Plan: Added unit tests. Lots of `grep`.
Reviewers: btrahan
Reviewed By: btrahan
CC: dctrwatson, aran
Differential Revision: https://secure.phabricator.com/D7759