UI: Finish ElasticSearch search/sort/page for Vertices

Rewrite VertexListCtrl to support main ES operations
- TODO: re-incorporate edge following
- TODO: mirror to EdgeListCtrl
UI: Build table columns based on ElasticSearch results

Update VertexListCtrl to dyamically build table columns
based on ElasticSearch sort results.
UI: Fix table header template to support groupBy method
Merge pull request #41 from kylef-lab41/master

UI: Finish ElasticSearch search/sort/page for Vertices