Title: Enable EJB 2.x Container-Managed Persistence

Describe the issue:
Just adding the extension <extension module="org.jboss.as.cmp"/> is not sufficient, it just imports the module but doesn't enable it.

Suggestions for improvement:
To fully enable the CMP subsystem, you also need to add the
        <subsystem xmlns="urn:jboss:domain:cmp:1.1"/>
element in the profile's xml config file, under the <profile> element.