MongoDB configuration added

Added:

* mongodb package to package.json
* configuration to use mongodb
* re-usable functions on Application controller

Instructions:

* after clone this version, run `npm install` to install dependencies,
  you may want to try a new version of `mongodb` package. If so,
  after `npm install` you can run `npm install mongodb --save`
Tests, jake tasks, documentation updated

Added:

* Tests for User model
* Jake tasks for run unit/integration tests
* Documentation
v0.0.6
Merge branch 'release/v0.0.6'