Add TCGA and color composition datasets to Qurro demos

[fedarko]

Not super urgent, but would be a nice thing to have -- all of the current demos are standard "microbiome" datasets.

This would require making a few changes -- I totally did this with the mackerel dataset in this PR but that was forever ago so I forget how to do that. Will require updating the python tests to add new integration tests, then modifying the gitignore to include the integration test outputs from the TCGA/color datasets in the repo, then modifying the demo site HTML to point to the outputs? Honestly, biting the bullet and taking care of #211 would make doing this in the future a lot easier...