Update instructions, notebooks to latest anaconda3 module

[bentsherman]

I have updated the instructions to use Palmetto OnDemand instead of JupyterHub, which is being retired. However, the instructions use a rather old version of anaconda3 and I'm worried it may be removed from Palmetto before long. At some point, someone needs to update the instructions to use a newer version of this module, and then test the notebooks -- create the conda environment from scratch, then run through all of the notebooks and make sure that they work.