Description of problem:
If a JBoss AS instance has had its data directory relocated or renamed, the JBoss AS plug-in fails to determine a valid Naming Provider URL (JNP URL) for the plug-in configuration for the newly imported resource. 

Version-Release number of selected component (if applicable):
JON 2.4.1

How reproducible:
Always

Steps to Reproduce:
1. Install a fresh EAP server
2. Start it an alternate location for its data directory:
   ./run.sh -c default -b 0.0.0.0 -Djboss.server.data.dir=/tmp/data/eap/default
3. Discover and import the new EAP instance
  
Actual results:
The AS resource is imported but it is marked DOWN and the JNP URL is not set under <resource> -> Inventory >> Connection. The agent also logs the following warning:
WARN  [ResourceDiscoveryComponent.invoker.daemon-847] (org.rhq.plugins.jbossas5.ApplicationServerDiscoveryComponent)- Failed to read JNP URL from '/opt/jboss/eap/jboss-eap-5.1/jboss-as/server/default/data/jnp-service.url'.

Expected results:
The AS resource is imported and the JNP URL is correct. The value should be read from /tmp/data/eap/default/jnp-service.url

Additional info:
This issue is cause by the assumption that the data directory is fixed or the presence is required by AS. Instead, this value is determined based on configuration of the AS instance itself and if not explicitly set, will default to ${jboss.server.home.dir}/data. The plug-in should not assume the default and instead use the value provided by the system property ${jboss.server.data.dir} and if not set, fall-back to the current behavior.