Adds not working D3 force-directed graph
Adds not working D3 force-directed graph

- JS data transformation that turns in-toto layout into data
  suitable for D3 graphs (will probably move transformation to server)
- A mostly copy pasted, not yet working D3 froce directed graph
  (will probably use a different library, e.g. dagre-d3)

in-toto/layout-web-tool,in-toto/layout-web-tool,in-toto/layout-web-tool