Test suite setup improvement

Refactored test suite setup
* Adjusted namespace definition in composer.json
* Corrected namespaces in Neo4jClientMock, as \ before fqdcn are not required when using namespaces correctly
* Added a .travis.yml file for using Travis and having a real db to test on
* Added a Import file to import data when the Slim bootstrap is done

I just need to look a bit deeper of how to bootstrap the app correctly for integration tests.

Running `phpunit` is ok.

Would be cool if merged to add `Travis` service webhook
5.3 is EOL. But ok :)