Arvados

reviewing commit:66f0448c8e5fe18ff7680c1009b82f2874fdb8bd on branch develop in the arvados-www repo:

• did we write tf-mnist-tutorial.py or is that from somewhere else? If the latter, we should probably attribute/make license clear.

• the "are available on Arvados playground" link should probably include a "the" before Arvados. Also, because of bug #18965 this link is basically useless, everyone will land on their home page after logging in. I suggest fixing #18965 urgently.

Finally, a process note: I think it would be better to just make a feature branch like always for stories like these, so that we can follow all our normal processes (albeit in the arvados-www repo). All developers should know how to run a local copy of the website for review (and it's documented on the hacking page I think).

Otherwise, LGTM, thanks!