Update node 0.10 recommendations to node 0.12

[alexwoehr]

I am finding some situations in the docs where 0.10 is recommended. Based on docpad/docpad#913, I am preparing a pull request to update these places to recommend node 0.12 or io.js.

[alexwoehr]

Cannot assign myself; no prob though.

[balupton]

@alexwoehr added you to the documentation/meta team :-)

Yep all references should go to Node 0.12 for now.

Ideally, we would switch to io.js, however I think that would be too big of a jump right now, as io.js is still a minority and new thing.