Config script should offer option to load existing git checkout

[cambot]

I have been iterating and experimenting with setting up a project with this module. I already had a checkout of my repo locally that I wanted to use, so I set up the root folder to my existing checkout. When it came time to the clone step, the config script skipped the prompt and did not load the existing project. when I opened the settings panel, I was presented with the default settings, which would overwrite what I have in git. Additionally, there is no way for a user to manually load a settings file.

It would be nice if the config script detected the target folder was not empty, then it would prompt the user if they should load the contents. It probably could be smart about detecting a .git folder and the config json file first. Maybe this could be an option in the clone menu? I am not 100% sure what I would want that workflow to look like. I only know that it is an option not yet accounted for.

It also seems like this functionality would also be helpful when setting up additional namespaces/productions on a given iris instance.

[isc-pbarton]

This is a more general case of the feature requested in #341, so I am letting this issue supersede that one.