Let's call it "sprint 0"

It's almost working (you have to install "now", "mongojs" and "send" npm packages), but there are few things I want to finish, before we merge this into master and start adding new features.

- ~~Document everything with jsdoc and markdown.~~

  I'd like to be able to generate both traditional documentation and annotated code.

- ~~Create package.json for npm with run and dev dependencies.~~

- Look around if mongojs is a good thing to go with.

  It really bugs me that that API uses just one callback (with `error` attribute), instead of two: `success` and `failure`. That's why I created `dbResponse`, but that's far from elegant…

- Make sure all method's parameters are sanitized.

- ~~Distribute info about new user entering the day to all users that are displaying it.~~

- Remove that TODO from `server.js`.

  If something is not done within this pull request, we should create an issue for it.

- Split server.js into smaller parts, maybe?

/cc @mkasprzak