Fix JCA description providers for the improved validation in jboss-as-subsystem-test

I added some tests called DataSourcesSubsystemTestCase, JcaSubsystemTestCase and ResourceAdaptersTestCase, which uses our subsystem testing framework which attempts to validate the description providers, this will be committed to upstream in the next few days.
To make the tests pass I had to override AdditionalInitialization.getModelValidationConfiguration() and isValidateOperations() as follows:

           @Override
           protected ValidationConfiguration getModelValidationConfiguration() {
               return null;
           }


            @Override
            protected boolean isValidateOperations() {
                //TODO fix providers https://issues.jboss.org/browse/AS7-1789
                return false;
            }

Returning null basically turns off validation of the providers, and the isValidateOperations() override turns off validation of the contents of the actual operations. What I have added is a minimum of what is required for subsystem testing, the test framework allows you to do a lot of other stuff, see the jmx subsystem test for some examples.

The wip lives at https://github.com/kabir/jboss-as/tree/subsystem-test-model-fixes