Make organism selector more configurable

[Smeds]

I’ve been experimenting with GenomeArk2 and added the organism selector to its landing page. While doing that, I identified several potential improvements/features I’d like to see. Most of these are focused on making certain parts more configurable:

1. logo part is hard coded to: .attr("href", "/logo/brc.svg")
2. data loading is hard coded to import data from "catalog/ga2/output/ncbi-taxa-tree.json";

It would be great if we could specify which values to use in a config file, or alternatively use the appKey (e.g., appKey: APP_KEYS.GA2) to determine which value to select.

Also if we could make the starting level configurable somehow. For GenomeArk2 it looks like this:

and I would like to be able to start at for example Metazoa, either that the selector zoom into that level or filter away the levels before this.

It would be kinda nice to at least be able to easily configure the logo and data import for the VGP meeting in end of Sept.!

@dannon @NoopDog