Update for compatibility with the new Layered Services data model

[cdelafuente-r7]

This PR updates the service lookup in #create_credential_service to also include the service name. This change is needed since now the service name defines a unique service. Services with the same host, port and proto but with different names a now considered separate services. Note that this also applies to the new resource field. I haven't added the resource in the lookup since it doesn't seem to be necessary for now. Please, let me know if you think otherwise.

Some considerations:

• a service without name is still possible (the name field is nil) and the same rule applies. Two services with the same host, port and proto, but one with a name and the other without, will be considered as two separate services.
• a service without resource defaults to an empty JSON {} and the same rule applies. Two services with the same host, port, proto and name, but one with a specific resource and the other without (empty JSON), will be considered as two separate services.

This PR also update the pwdump file to import in specs. The format was not parsed correctly by the pwdump parser and caused unexpected service creations. I tried to keep it consistent with the original regex:

# <IP address>:<port>/<proto> (<service name>)