Revision 1058247

Implementation fix and acceptance tests for protocol recommendation:

"Many HTTP/1.0 cache implementations will treat an Expires value that
is less than or equal to the response Date value as being equivalent
to the Cache-Control response directive "no-cache". If an HTTP/1.1
cache receives such a response, and the response does not include a
Cache-Control header field, it SHOULD consider the response to be non-
cacheable in order to retain compatibility with HTTP/1.0 servers."

http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.9.3

Also had to update a few other test cases that incidentally ran afoul
of this recommendation.