git repo cache to not complete download from git repo every time

[bradymiller]

Do plan to hopefully attack this issue down the road to improve efficiency (will basically keep a “cache” of repositories that have been used and update that “cache” git repo rather than completely download it, if it exists; being able to use volumes on dockers makes these kinds of things much easier to support). This will involve substantial work for not a huge gain (aws does not charge for this huge amount of incoming data, so it basically just speeds up the time it takes to reset the demos), so it’s a future todo.

[bradymiller]

Also should migrate the initial pull of the demo farm repo (from dockerfile build) to instead using a docker volume (this means would not need to clone this repo every time and instead woudl just need to update the repo on the host).