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
Maybe obvious, but before starting describing the limitations I would clearly state what they apply to Service, ServicePath and Entity (i.e., when we use the word "element" in this section, we refer to these three concepts).