Extensible Metacard unregister and list registered types functionality.
DDF-49: MetacardTypeRegistry immutability of registered types set.  Clean up of logging statements.  Test comparing a QualififedMetacardType with a MetacardType.
Merge pull request #3 from codice/ddf-extensible-metacard

DDF-49: Merge the ddf extensible metacard functionality into master.