Add tests & bugfixes for user router

[Timothy-Gonzalez]

Resolves #94

This covers most of the code and edge cases that I think are reasonable to test. Only things not covered are mongod errors, but those are harder to test.

Tests for:

• GET /user/qr/
• GET /user/qr/:USERID/
• GET /user/
• GET /user/:USERID/
• Remove POST /user/

Also applies a few misc bug fixes, namely typo stuff & returning wrong values.

Coverage from latest commit:

 src/services/user       |     100 |       95 |     100 |     100 |                                                                                                                                                                                 
  user-router.ts         |     100 |       95 |     100 |     100 | 111         

[AydanPirani]

Had some questions + suggested changes with HTTP codes

[AydanPirani]

lgtm! one thing we should do - add in a status code at some point