RFR 8042622: Check for CRL results in IllegalArgumentException "white space not allowed"

[Michael McMahon]

http://cr.openjdk.java.net/~michaelm/8042622/webrev.1/

The issue is that ResponseCache is receiving all the headers from our
MessageHeader internal implementation class. This includes
a dummy/fake header that represents the request line of a request
(eg GET /foo.html HTTP/1.1) and this is causing problems later
on for the URLPermission class because the fake header name has a space 
in it.

The fix is simply to only include user set headers (which are already
maintained in a separate MessageHeaders instance) when calling
into the ResponseCache object. Strictly speaking, a minimal fix here
would just remove the dummy header, but I think it makes more sense
to only include genuine "user set" headers, rather than system set ones.

Thanks
Michael