Set a non-zero exit code when error in command parsing

[drcrallen]

This is helpful for things like automated build scripts that should fail if a command syntax changes, and the script does not notice. Without this change a script may think the command completed successfully.

[gianm]

👍

[drcrallen]

Tests run: 5, Failures: 0, Errors: 1, Skipped: 0, Time elapsed: 67.041 sec <<< FAILURE! - in io.druid.curator.announcement.AnnouncerTest
testSanity(io.druid.curator.announcement.AnnouncerTest)  Time elapsed: 61.047 sec  <<< ERROR!
java.lang.Exception: test timed out after 60000 milliseconds
    at sun.misc.Unsafe.park(Native Method)
    at java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:226)
    at java.util.concurrent.locks.AbstractQueuedSynchronizer.doAcquireSharedNanos(AbstractQueuedSynchronizer.java:1033)
    at java.util.concurrent.locks.AbstractQueuedSynchronizer.tryAcquireSharedNanos(AbstractQueuedSynchronizer.java:1326)
    at java.util.concurrent.CountDownLatch.await(CountDownLatch.java:282)
    at org.apache.curator.test.Timing.awaitLatch(Timing.java:120)
    at io.druid.curator.announcement.AnnouncerTest.testSanity(AnnouncerTest.java:101)

[fjy]

👍