Proper entity URL management for light308 demo

[asorici]

Context

The current implementation of the demo light308 context-based access scenario has small hacks that require rewriting the requestIRI / requestURI in several handlers - handleUpdateEntity() in RdfStoreVerticle, updateRepresentation() in AuthHue - to include or exclude the port number in the request, depending on how the server is launched.

The issue stems from the fact that in the MainVerticle configuration for the demo (e.g. artifactPolicyConfig) the URL path for the light308 artifact is hardcoded without any reference to the configuration with which the Yggrdasil platform is launched (src/main/conf/config_hmas_upb.json) - and specifically the host and port configuration.

Steps

• Use the host and port values in the config_hmas_upb.json to correctly anticipate the URI of the resource that will be created following the CreateEnv --> CreateWorkspace --> CreateArtifact procedure
• test that the created artifact paths (involving actions that need to be invoked) are all uniform
• fix the TODO assignments in the handeUpdateEntity() method in RdfStoreVerticle, and the updateRepresentation() in AuthHue once uniform access and referencing is ensured