Generate json file that handles multimarker learning for all users

[dschonholtz]

I'm on a bus and I don't have stable enough light, internet connection or markers to work on the other things that I want to work on so I hope y'all like issues.

(Sorry that's unrelated, slack isn't working either)

It looks like if users want to use multiple markers they have to learn locally.
This generates a json file such that when the app isn't in learning mode it knows how to interpret the markers in the multi marker. What we should do is make it so the majority of our users just get that json file and they don't have to deal with that learning process which wouldn't be a good part of the scavenger hunt.
https://github.com/jeromeetienne/AR.js/tree/master/three.js/examples/multi-markers