[WFLY-3534] - Updating code to reflect changes from transaction subsystem.
WFLY-3189 - Do not use schema location in schema element. Do not use
schemaLocation when importing a namespace.

XML validators seem to get confused when schema location is specified
and imports / includes are circular. Instead rely on entries in XML
catalogue.
WFLY-3189 - Add XML schema for namespace "urn:clustering:1.0" which is mentioned in
https://docs.jboss.org/author/display/AS71/jboss-ejb3.xml+Reference, but
missing this plugin and in JBoss EAP 6 distribution. Based on
"jboss-ejb-security_1.0.xsd".