color/background image randomization and consistency for dataset entries

[andersy005]

          So many colors!

It might be worth flagging that with so many colors this treatment might seem less like a random pattern and more like a specific image for each entry.

Unless new entries will automatically get added to the end of the list of filteredDatasets, it seems like each dataset's color could get shifted whenever a new dataset is added. Also because of the filtering logic in Catalog, I think the colors will change as the search bar is used.

No strong feelings here, but it might be worth thinking about whether we want colors to feel obviously randomized and/or a little more "pinned down" for each dataset.

Originally posted by @katamartin in #19 (comment)