[ARIES-1012] Properly isolate the subsystems core bundle.

Private packages are no longer exported. The itests now attach a fragment to the core bundle in order to get
access to those private packages.

git-svn-id: https://svn.apache.org/repos/asf/aries/trunk@1441607 13f79535-47bb-0310-9956-ffa450edef68