Implement communication protocol between SensorNode and ManagementNode

[asorici]

Why

Because there has to be one, obviously :-)
The ContextDomainGroup managed by a ManagementNode needs to be modeled as a ThingDescription entity, as well.

What

• implement 3 default Thing description properties
  • the GET on a base representation URI (http://<baseUri>/coord/location/<domainName>) returns the description of the ContextDomain
  • the GET on <baseRep>/providers returns the list of registered SensorNodes
  • the GET on <baseRep>/capabilities returns the list of capabilities (ThingDescription modeled devices)
• implement 1 ThingDescription action - join - by which SensorNode can register itself and its capabilities (the devices it manages, modeled as ThingDescription entities)

Notes

All communication payloads are transmitted as RDF triplets.