Rederly demo

Glad to learn that Rederly is going to take the WeBWorK Open Problem Library and utilize it in a new platform.  The project is open source, but seems that they also sell it as a service.

Took it for a spin. The renderer seems solid. Backend has some strange design but overall ok.  At least it makes sense when you look at the code.  Some functionalities still missing (e.g. class enrollment by admin) or require tuning (e.g. listing the whole class of several hundred students is going to be slow) though.

Wrote some scripts to run the full stack (frontend, backend, renderer, and db) as containers.  Also tested it on Azure with docker-compose (with minor changes on disk volume mount).