db: Create 'User' model
Update README.md
Implement passwordless - first stage

There is still work to do:
- the restricted access is always restricted
- need some refactoring, it's just a demonstration that it actually
  works
Fully working passwordless

TODO:
- tests
- refactoring
Remove unnecessary code and create 'test' task in Grunt

The current code still using the faked database with no ability to add
new user to it. We are waiting for MongoDB implementation which will be
provided by Bartek.
Almost finished the implementation