Use nodeenv via tox to do javascript testing

The OpenStack CI systems like things that run in virtualenvs. This moves
the first stab at running javascript unittests from custom in-tree scripts
to being based on tox and nodeenv. Additionally, it publishes the dist
dir from the tree to docs-draft, because the dist contents should be the
compiled, minified and fully-functional web code, and it should be directly
verifiable on a passing commit.

Change-Id: Id48ee2524d846b5e08ca94f485f8d67abbd3681a
Merge "Use nodeenv via tox to do javascript testing"