Feature/graph kingdom

[danielabar]

• Modify api call used by network controller to get source and taxon path fields
• Determine taxon kingdom from source or target taxon path.
• Map kingdom to shape for column graph vis.
• Implement d3 extension to support custom symbols

  Outstanding (will do in separate PR)

• Actual star shape, for now its a simple x mark to demonstrate the concept of d3 custom symbols
• Kingdom legend