UI: Add link following to updated VertexListCtrl
UI: Display vertexFrom info when link following
UI: Set vertex._id from ElasticSearch results
UI: Display vertex options based on single/many selected

VertexListCtrl enables modification of vertices and edges
based on whether zero, one, or many vertices are selected.
Merge pull request #51 from kylef-lab41/pr-vertexlinkfollow

Vertex link following