[ARIES-996] JPA does not work for bundles that are constituents of subsystems.

A bundle tracker was added to track the region context bundles of subsystems. When a context is registered, these bundles are
examined to see if one is visible to the client bundle. If so, that region context bundle is used to establish the relationship
with a persistence context manager. If no subsystem region context bundles are present, the behavior is the same as before.
Composite bundle frameworks are still supported as well.

git-svn-id: https://svn.apache.org/repos/asf/aries/trunk@1429829 13f79535-47bb-0310-9956-ffa450edef68