Experimented with user authentication and refactored into separate
packages the code to divide
the core module from the integration code.
The code now references a more generically named variable MONGO_URI
instead of the vendor specific MONGOLAB_URI.

- Changing the MongoDb provider is a matter of changing property files and
  system variables anyway, but should this now happen, the name of the
  variable makes more sense. In fact in development it did not make sense
  since the database is running locally and not using a SaaS MongoDb
  provider.