Adding Models and Settings Module

Here some work that we do for the integration with Compropago. Basically we refactored some part of the code in order to make it maintainable and stable. We included active-rest-client that depends of faraday and allows to make effortles advanced HTTP requests, hope that you like it :grin:.

Pending TODOs:

- add more tests
- handling errors, would be nice to raise custom errors like Compropago::Error