Copy harness directory rather than cloning

We discussed this in a meeting, but I thought I would make an issue.

When running the go-button, the harness currently makes the other nodes clone the master branch of the harness repo. Instead, it should copy the local copy of the harness repo so all the worker nodes have any local changes you've made to the harness. This will help with the issue of pushing before testing or wondering why saved but un-pushed changes are having no effect.

I don't remember what method of copying we decided would be good. Rsync? Scp? Something like that. But not git -- we want saved but untracked changes to be copied too.