convert net crate to use hyper
convert msg crate to use hyper
convert script crate to use hyper
adjust WPT since hyper fixed some
auto merge of #4065 : seanmonstar/servo/hyper, r=Manishearth

Replaces `rust-http` with [hyper](https://github.com/hyperium/hyper).

I don't have any bench numbers: I'm not sure what I would run (before and after) to make a nice presentation. If someone could help me there, I can update this description.

WPT-wise, ~18 more tests succeeding.

So say we all?

Closes #3956