don't fail on unicode js newlines (\u2028, \u2029)

If you ask me what is the most stupid standard in JavaScript world, I'd say JSON is second to none.

No comments allowed, no trailing commas (which constantly screws up git diffs), no good Date representation, `\v` is confusingly missing... did I forget anything?

Oh right, and JSON.stringify is broken in a way that its output can't be embedded in the JavaScript source code as is.

Bug report:
https://github.com/visionmedia/jade/issues/1648

Details:
https://code.google.com/p/v8/issues/detail?id=1907

Same fix as in:
https://github.com/strongloop/express/issues/1132