uses schema indices only for selected node labels
Merge branch 'master' of http://github.com/buschmais/jqassistant

Conflicts:
	core/store/src/main/java/com/buschmais/jqassistant/store/api/model/NodeLabel.java
	core/store/src/main/java/com/buschmais/jqassistant/store/impl/AbstractGraphStore.java