Add JMS bridge to Messaging subsystem

Currently there is no pre-defined way to deploy a JMS bridge (i.e. org.hornetq.jms.bridge.impl.JMSBridgeImpl) in AS7. In JBoss AS 6 and earlier you could deploy the bridge as an MBean or JBoss MC bean, but the current configuration schema in AS7 simply doesn't support it. The bridge is a nice feature so we need a way to deploy it.

It doesn't make sense to add the JMS bridge to a <hornetq-server> because the bridge can operate independently of a local HornetQ server. It really needs its own subsystem.