Implemented the bases of the application that now looks like a MVC application
- Implemented the infrastructure of url mapping, that converts urls to calls on controllers classes methods
- Implemented the functionality that allows to connect to the database, with the possibility to extend the
  application to use different adapters (default and actually implemented is postgresql).
- Implemented the 'find' static methods for the classes that extend the Model class. The 'find' method
  allows to execute queries by passing an array of params as argument, or by passing nothing, that returns
  all the elements of the associated relation.
- Created the base layout of the application by using the bootstrap library.