JMX's ServiceControllerContext doesn't use MDR

[alesj]

We're currently not registering ServiceControllerContext to MDR.

Looking at its DescribeAction, it's a no-op.

We used to populate KernelControllerContext's MDR in Describe state,

so I guess this is the right place to populate it.

(we moved the POJO MDR population to PreInstall due to scoping)

[alesj]

This needs fixing first:

* http://community.jboss.org/message/316423#316423

Otherwise we always need to add such "hack":

* repository.addMetaData(context);

* repository.getMetaData(context); // <-- THIS is actually the call that populates it