ARIES-1215 - Use system bundle for tracking namespace handlers and bundles

If the property org.apache.aries.blueprint.use.system.context=true is set 
then the blueprint extender will use the system bundle context to track blueprint bundles
and track NamespaceHandler services.

Two new testcases were added.

1) verifies that if a blueprint bundle is hidden
from the blueprint extender, using bundle hooks, then the blueprint extender can still
track the bundle properly using the system bundle context

2) verifies that if the blueprint cm bundle is hidden from the 
blueprint extender, using service hooks, then the blueprint extender can still
process blueprint bundles that use the cm namespace handler properly

When org.apache.aries.blueprint.use.system.context=true the blueprint extender
will no longer use the RecursiveBundleTracker.  This means that the old 
equinox composite bundles will not be supported when this option is enabled.
This option is intended to be used with subsystems.



git-svn-id: https://svn.apache.org/repos/asf/aries/trunk@1609727 13f79535-47bb-0310-9956-ffa450edef68