PLUGWEB-15: fix testErrorPageDecoratedCorrectly(), so that it asserts for the right thing
PLUGWEB-15: fix testContentLengthSetCorrectlyWithNoneDecorator()'s assertion about content length
PLUGWEB-15: make note on how to run integration tests
PLUGWEB-15: make PageResponseWrapper inspect a request attribute at the last minute, to disable buffering and decoration
PLUGWEB-15: unit test to ensure buffer is not used when sitemesh is disabled with request attribute