JERSEY-2206: "Processing of header changes in a WriterInterceptor"
JERSEY-2123: "ApacheConnector MultiPart file upload - no multipart boundary was found"
Connectors log warning whenever headers (requested vs. really send) differ.
ApacheConnector and JettyConnector are not public classes anymore.

Change-Id: Ie338bd0707049b2866f41fc084495341d20e1d90