Semi-fix git cloning for non-bare repos for landing

Summary:
If the repo isn't bare, than we need copy it's remote instead of using it.

This will probably not work if an SSH key is provided to phabricator, and in any case you must delete
all workspaces that were already created.

This will make landing those repos slower; I plan to just delete and re-clone all repos on my instance.

It will probably be simpler to just make a bare-repo a requirement of all the git-landing work.

Test Plan: landed from hosted and un-hosted repos, checked git-remote url in each newly cloned workspace.

Reviewers: epriestley, Blessed Reviewers

Reviewed By: epriestley

CC: Korvin, epriestley, aran

Differential Revision: https://secure.phabricator.com/D7592