First implementation of ObservationReader. The SPARQL query for
observations in the KB is still buggy.
Added ObservationReader implementation and example topology
No query for types in getObservations() to avoid observation duplicates
in result sets. This is a temporary fix, not really a solution.
Removed unused limit variable
Updated RDF Data Cube Vocabulary (cube.ttl)
Removed from project
Added test case for ObservationReaders in topology