Refactor Configuration interface, add mock for it and add controller test

[caiopiccirillo]

First of all, this PR is target to your branch no-json-in-config-injection, so I created this separate PR so we can review this particular changes. I was thinking about the config interface and it doesn't need to know which kind of serialization we need. In the end I added a test example for Controller, we need to extend it to cover all kind of scenarios. I want to go through this changes with you, because I'd like to know if you agree 😄