I'd like to use the UrlRouter as demonstrated in the various examples.  
However, the delegates it maps urls to only take an HttpServerRequest and 
an HttpServerResponse and I can't find any way to get at the request's 
HTTP headers.  Specifically, I'd like to check the "Accept" header and 
render different versions of a template accordingly.
Is there a reason headers are not included in the HttpServerRequest class?
Justin
