Force Directed Graph with 2 fixed nodes
forked from arpitnarechania's block: Force Directed Graph
Modified http://d3js.org/d3.v3.min.js to a secure url
https://d3js.org/d3.v3.min.js
https://code.jquery.com/jquery-3.1.1.min.js
https://cdnjs.cloudflare.com/ajax/libs/d3-tip/0.7.1/d3-tip.min.js