trireme should support http IncomingMessage.rawHeaders

[asquare]

Node and Trireme convert all http headers on the incoming request to lowercase. However, some applications require access to the original unmodified headers. Node's http module introduced IncomingMessage.rawHeaders to provide access to the unmodified headers. This property is present in 0.12 and not in 0.10. Even though Trireme is compatible with 0.10, it should make this property available for enhanced compatibility.