bugfix worker DriverStateChanged state should match DriverState.FAILED

bugfix worker DriverStateChanged state should match DriverState.FAILED

Author: lianhuiwang <lianhuiwang09@gmail.com>

Closes #864 from lianhuiwang/master and squashes the following commits:

480ce94 [lianhuiwang] address aarondav comments
f2b5970 [lianhuiwang] bugfix worker DriverStateChanged state should match DriverState.FAILED

core/src/main/scala/org/apache/spark/deploy/worker/Worker.scala

@@ -317,10 +317,14 @@ private[spark] class Worker(
       state match {
         case DriverState.ERROR =>
           logWarning(s"Driver $driverId failed with unrecoverable exception: ${exception.get}")
+        case DriverState.FAILED =>
+          logWarning(s"Driver $driverId exited with failure")
         case DriverState.FINISHED =>
           logInfo(s"Driver $driverId exited successfully")
         case DriverState.KILLED =>
           logInfo(s"Driver $driverId was killed by user")
+        case _ =>
+          logDebug(s"Driver $driverId changed state to $state")
       }
       masterLock.synchronized {
         master ! DriverStateChanged(driverId, state, exception)