Bump shipping node version #

As part of the release activities, and getting things building. @markcowl and I had a discussion about the version of node we're shipping in the mac installer. 0.6.17 is ancient (in node years, anyway). Node version managers (like nvm and n) don't support versions that old. And we're all using 0.8.something anyway.

So we decided it would be reasonable to update the version of node in the mac installer to 0.8.22. This PR makes that update.