Implement better logging

[lukas-shawford]

Need to add error logging to the app. Errors (and possibly all requests) should be persisted to the database on the live site, whereas in dev, they should just be dumped to the console. Additional metadata such as current user and quiz/topic should get logged along with the error wherever possible.

As for choice of logging framework, it will probably either be winston.js or bunyan. here are some resources that may be useful in making the decision:

• Comparing Winston and Bunyan Node.js Logging
• Node.js in production: runtime log snooping (Bunyan)