Storing these in Git seems kind of weird, but seems to be [1] the done thing.
I have to say, it's a lot more appealing than getting 3 packages from npm
installed globally on every prod and dev machine -- we already have too much of
that with 'pip install'.
We can upgrade these in the future by running 'npm update' in the repo root
directory.
[1] http://www.futurealoof.com/posts/nodemodules-in-git.html
(imported from commit 60a9d6a7cafe742442d87e9f3abc25750e179780)