New thread introduced by hbase-900 part 4 is not daemon so can cause JVM to stick around on abort

"pool-1-thread-1" prio=10 tid=0x00007f582805c800 nid=0x6fd waiting on condition [0x00000000436a7000..0x00000000436a7c00]
   java.lang.Thread.State: WAITING (parking)
        at sun.misc.Unsafe.park(Native Method)
        - parking to wait for  <0x00007f583b3578e0> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
        at java.util.concurrent.locks.LockSupport.park(LockSupport.java:158)
        at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:1925)
        at java.util.concurrent.DelayQueue.take(DelayQueue.java:160)
        at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:583)
        at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:576)
        at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:947)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:907)
        at java.lang.Thread.run(Thread.java:619)