[CXF-4986] Fixing MetadataMap to enforce the read only for stores which are not copied and all 2.0 filter contexts to set a proper flag on it; using HttpServletRequest to save the filter properties if possible

git-svn-id: https://svn.apache.org/repos/asf/cxf/trunk@1476142 13f79535-47bb-0310-9956-ffa450edef68