Add support for more node/edge attributes, provide array of nodes and edges as component parameter

[victor-nitu]

Add support for:

• node size (value)
• edge thickness (value)
• edge color (color)

Now it's possible to provide an already build array of nodes AND an array of edges like this:

{{#visjs-network options=networkOptions nodesSet=model.graph.nodes edgesSet=model.graph.edges}}
{{/visjs-network}}

And also like this:

{{#visjs-network options=networkOptions}}
  {{#each model.graph.nodes as |node|}}
      {{visjs-node nId=node.id label=node.label value=node.value color='rgb(39,239,252)'}}
  {{/each}}
  {{#each model.graph.edges as |edge|}}
    {{visjs-edge from=edge.from to=edge.to value=edge.value color='rgb(49,57,57)'}}
  {{/each}}
{{/visjs-network}}

I haven't tested what happens if you provide both, probably some exception should be raised not allowing it, or maybe the component nodes/edges defined via hbs should be added to the provided arrays. To be determined :-)

Thanks for all the work on this, I'm going to remove my previously created PRs that are now a part of this bigger, improved one.

[navkast]

@Suven - do you still maintain this? This looks like a good feature.