Add Testing Suite

[vincent-maillou]

Currently, the framework is being tested through convergence of integration tests present in the example folder. Unitests can be added and/or more specific integration tests (testing for the model pipeline independently of the optimizer, for example).

[vincent-maillou]

The testing suite is far from being finished, but it is going to be a long process, and at least more than the initial scaffolding is there.