Develop ROSJava based Node for CONSERT Engine

### Why
We want to extend the existing knowledge-driven reasoning in the CONSERT Engine with probabilistic reasoning.
Because it is unlikely that prototyping of the data-driven inference algorithms will occur in Java, a means to communicate with the CONSERT engine is required.
Since an objective in the ROBIN project is to create a ROS-based deployment for the CONSERT Middleware, it is important to prototype the first use of ROSJava in the CONSERT Project.

### What
- [x] Implement a ROSJava Node that constitutes the runtime of the CONSERT Engine
- [x] Define and implement the ROS Message templates that capture the semantics of the CONSERT Ontology: define message templates for the ContextAssertion, ContextEntity, ContextAnnotation and EntityDescription concepts
- [x] create conversion code to/from POJO form to rosmsg form
- [x] implement _output_ topics (one per context assertion type) that continuously update the situation ContextAssertion situation instances, including the ones that _**indicate possible events for a given data-driven inference**_
- [ ] implement an _input_ topic for the engine
- [ ] implement a _data-driven result input_ topic for the engine, where results of the data-driven inference processed are returned to the engine

### Notes