Properly remove expired JBoss XSDs and DTDs files from JBoss Metadata

JBoss Metadata resource contains some expired XSDs and DTDs files of previous AS versions. for example : jboss_5_0.xsd and jboss_5_1.xsd.
These old files should be properly removed and not published in schema directory in dist.
Meanwhile, it's prefer to add some additional parser tests that could assure the existence of old spec descriptors.