Grading PR with comments and feedback [DO NOT MERGE]

[martypdx]

Over very ambitious project with nice functionality. Biggest thing is keeping the code refactored and clean to make it easier to work with.

• A lot of good effort in testing!
• Promise chaining went off the rails in the longer, more complicated uses. Need to refactor and rework to not create "big balls of mud"
• clean up: remove console.log, unused imports, dead files.
• Don't use variables to pass state between steps in promise chain, unless you need to preserve data from a prior step for use in a later step. That technique is a "last resort", not a go-to.
• For a data server, avoid string based requests and responses (wrap in an object)
• Use .lean() and .select() on your GETs
• Move logic to model when it makes sense (look for long code in routes)