Added 5-10 REST methods (GET, POST).
All GET methods of organizations ressource are finished.
Created SensorRessource and added 3 GET and 2 POST methods.
Created DtoConversions file and moved the DTO conversion methods there, refactoring them as static.
Added some more DTO conversions methods.
Modified InitRessource to create initial observations.
Added DTO objects: ObservationDto and SensorDto.
Added some JPQL NamedQueries.