Update npm-shrinkwrap.json

I'm not really sure I understand the mechanism by which this is out of
date or even what the changes here imply, but this is the result of
running

    npm shrinkwrap --dev

with latest npm (3.10.5), and the output appears to be stable --
multiple runs do not change it further.

In addition, installing new packages and rerunning `npm shrinkwrap
--dev` appears to generate a minimal diff after this one-off update.