backlog/207_212_fiware_service_path

This issue implements/fixes several backlog features and issues:

* Use the `fiware-servicePath` header (https://github.com/telefonicaid/fiware-connectors/issues/212)
* Common character set when naming persistence elements (https://github.com/telefonicaid/fiware-connectors/issues/207)
* The organization is not created in column mode anymore (https://github.com/telefonicaid/fiware-connectors/issues/181).

DO NOT MERGE YET
Not sure in which part of the code to look :), but just to be sure... have you included unit test to check that ServicePath, ServiceLevel and Entity limitations (lenght and characters) are enforced?