Description of problem:
EAP 5 could disable EJB timer service persistence by NoopPersistencePolicy. However, EAP 6 does not have setting to disable persistence configuration.

Version-Release number of selected component (if applicable):
JBoss EAP 6.1.0

How reproducible:

Steps to Reproduce:
1. Remove data-store attribute in timer-service subsistem.
ex) standalone.xml 
  <timer-service thread-pool-name="default">
<!--
    <data-store path="timer-service-data" relative-to="jboss.server.data.dir"/>
-->
  </timer-service>

2. Start EAP 6 server
3. You can confirm following exception.
ERROR [org.jboss.msc.service.fail] (MSC service thread 1-1) MSC000001: Failed to start service jboss.ejb3.timerService.fileTimerPersistence: org.jboss.msc.service.StartException in service jboss.ejb3.timerService.fileTimerPersistence: Failed to start service
	at org.jboss.msc.service.ServiceControllerImpl$StartTask.run(ServiceControllerImpl.java:1767) [jboss-msc-1.0.4.GA-redhat-1.jar:1.0.4.GA-redhat-1]
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) [rt.jar:1.7.0_25]
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) [rt.jar:1.7.0_25]
	at java.lang.Thread.run(Thread.java:724) [rt.jar:1.7.0_25]
Caused by: java.lang.IllegalArgumentException: JBAS014747: abstractPath is null
	at org.jboss.as.controller.services.path.AbsolutePathService.convertPath(AbsolutePathService.java:81)
	at org.jboss.as.controller.services.path.PathManagerService.resolveRelativePathEntry(PathManagerService.java:85)
	at org.jboss.as.ejb3.timerservice.persistence.filestore.FileTimerPersistence.start(FileTimerPersistence.java:116)
	at org.jboss.msc.service.ServiceControllerImpl$StartTask.startService(ServiceControllerImpl.java:1811) [jboss-msc-1.0.4.GA-redhat-1.jar:1.0.4.GA-redhat-1]
	at org.jboss.msc.service.ServiceControllerImpl$StartTask.run(ServiceControllerImpl.java:1746) [jboss-msc-1.0.4.GA-redhat-1.jar:1.0.4.GA-redhat-1]
	... 3 more

Actual results:
Even if data-store is not necessary for persistence, we must set it.

Expected results:
We need setting to disable persistence configuration.

Additional info:
If you do not need EJB timer service persistence data, you can delete persistence data file (standalone/data/timer-service-data/*) before EAP server re-boot.