Improve testing

[andyfry01]

Numerous things can stand to be improved in terms of testing:

1. Tests are currently written in one big file (spec.js), but would be easier to manage across multiple files.
2. Currently when running tests, and especially when using a mocha watch script, the test runner opens tons of DB connections, which can overload MongoDB and cause problems, requiring manually stopping and restarting the DB server.
3. Testing asynchronous parts of the code can be problematic, requiring hackey workarounds that are not CI-friendly and produce unreliable test results (for example, see here).