ENH: Working prototype of add_to_canvas behavior for query_dict

@NSLS-II/development-team Here is a working prototype of the desired behavior in VisTrails when a user wants to add their scan to a VisTrails canvas. See `example_vistrails/add_to_canvas_brokerquery.vt`.  That .vt file currently requires that you be on one of the computers at CSX with the devel branch on metadataStore installed.  I will continue to update this as I make progress, but have a look.
I thought the `NSLS2|` was part of the namespace, but all this does is nest everything under an additional heading.

Before:
NSLS2
   ∟NSLS2
      ∟io
      ∟broker
      ∟vis
      ∟ etc...

After:
NSLS2
   ∟io
   ∟broker
   ∟vis
      ∟ etc...