Provide a config module
Summary: Allow to configure the microservice.
Test Plan:
Refactored from API production code
After moving the config code to this crate:
2018-09-04T18:58:31Z: rocket::rocket: Rocket has launched from http://0.0.0.0:8000
Reviewers: dereckson
Reviewed By: dereckson
Differential Revision: https://devcentral.nasqueron.org/D1664