Initial tentative 3

Everything is set for the REST Connector:
- Definition
- Implementation
- UTs
- Build
- All in one (no Maven repository in the project)
- Functional tests on the Studio 6.3.6
Everything has been fixed based on the comments but:
- The parameters duplications: they are not public in the implementation then not accessible from the test class.
- Connectivity issues, server errors, item not found: will be done in further commits