changes on PropertyTypes; PropertyTypesTest
	- remove sites attribute
	- implement setPropertyTypeFromValues methods
	- write test class PropertyTypesTest
	- change version of org.apache.httpcomponents.httpclient
Merge branch 'rdf-serializer' of
https://github.com/Wikidata/Wikidata-Toolkit.git into rdf-serializer

Conflicts:
	wdtk-rdf/src/main/java/org/wikidata/wdtk/rdf/RdfConverter.java
	wdtk-rdf/src/main/java/org/wikidata/wdtk/rdf/ValueRdfConverter.java