[CXF-5000,CXF-5007] Delaying converting headeres to String till the stream is written (required), minor updates to do with AsyncResponse exceptions, support for reading streams into File (only to get TCK happy)

git-svn-id: https://svn.apache.org/repos/asf/cxf/trunk@1481920 13f79535-47bb-0310-9956-ffa450edef68