output figures in a snakemake report

[aryarm]

The classify pipeline creates several figures as part of its output. Snakemake has a report() function for marking these figures as such. Consider using it.

That way, the user could have the option of whether to generate the plots (rather than making them required outputs at the end of the classify pipeline). And, we could keep them in a nice, tidy HTML file for them to peruse whenever they're trying to test a trained model.