Merge pull request #87 from erickt/demo

Fix random graph endpoint, allow not_analyzed string ES keys
Revert "Revert ElasticSearchController"

This reverts commit c63f42296f18633fdf5eb57f92e96ae5e26229f5.
Allow searching/mapping against a branch
add exporting a graph subset to a new project.

Note this fixes the nstep subgraph, but it does so in a very
inefficient manner. We are currently walking N steps out from
each initial node, which may result in touching the same nodes
multiple times over. It would be more efficient to maintain a
queue of some sort to cut down on the number of visits we do
to each node.