Provide support for GraphFilter.vertexProperties()

rspitzer stated that he is working with a graph that has millions of vertex properties on a vertex. If those properties are not needed for the traversal, then they should be filtered out.

Much like GraphFilter.edges(), we should add GraphFilter.vertexProperties(Traversal<Vertex,VertexProperty>). That is, from the Vertex in question, traverse to those properties needed in the computation, where properties().limit(0) would be the push down predicate for "no properties." Another example, properties("income") would only provide income properties. Another example, properties("income").has("acl","public") would provide only those income properties that are public (according to access control).

— SIDENOTE. In the docs we have bothE().limit(0) as the predicate for no edges. However, limit(0) by itself is sufficient. Likewise for GraphFilter.vertexProperties().