Dropdown with SPARQL11 property path

Mostly to increase the loading speed for dropdowns, this commit uses
SPARQL11 to query dropdown data. However, SPARQL11 queries with property
paths are not recognized with the SPARQL parser of Erfurt. There is an
experimental Erfurt branch feature/property-paths-query which enables this
feature.
Merge branch 'feature/rdfauthor-FormBuilder-dropDownTestWithSPARQL11' into deployment/erm-hd