Fix regressions in test_negotiated_resource
Stop directly instantiating Website so much

Using the harness yield_fixture reduces console chatter (but dangerously
so!?)
Fix regressions in test_json_resources

Evolving how to deal with the need to reconfigure the website object
inside the test; the harness already has an instantiated website. We
solve it here with a remake_website(argv=None) method. Call that in any
test that needs to modify configuration first.
Fix regressions in test_http{basic,digest}
Fix remaining regressions in test suite