Upgrade Node version

[dereklieu]

Api is using v0.10.~

To stay with the state of the tech, we should consider an upgrade.

Node is on version 0.12.7, and IO.js is constantly moving.

cc @kamicut @anandthakker @olafveerman

[anandthakker]

👍 Yeah, 0.12 and iojs include more major advances than I've kept track of, but I do think they're certainly solid enough for production use. Let's do it.