added data primitives classes for the osm object representation
added missing comments
log tag changed, other minor fixes ref #2578
added more comments, some minor changes refs #2578
added junit test for OsmElement, Node, Relation and RelationMember #2578
added robolectric as dependency in pom.xml refs #2578
added comments, added robolectric for log messages refs #2578
added junit tests for way objects refs #2578
Finish 2578-Data-Model closes #2578 refs #2741

Conflicts:
	pom.xml