[SMX4NMR-315]provide a configurable way to specify the Karaf RolePrincipal classname when expose NMR DefaultAuthorizationEntry as OSGi service

git-svn-id: https://svn.apache.org/repos/asf/servicemix/smx4/nmr/trunk@1532662 13f79535-47bb-0310-9956-ffa450edef68