[hotfix] Register signal handler for JobManager and TaskManager

This closes #1400

flink-runtime/src/main/java/org/apache/flink/runtime/blob/BlobCache.java

@@ -203,6 +203,8 @@ public final class BlobCache implements BlobService {
 	@Override
 	public void shutdown() {
 		if (shutdownRequested.compareAndSet(false, true)) {
+			LOG.info("Shutting down BlobCache");
+
 			// Clean up the storage directory
 			try {
 				FileUtils.deleteDirectory(storageDir);

flink-runtime/src/main/java/org/apache/flink/runtime/util/SignalHandler.java

@@ -46,6 +46,7 @@ public class SignalHandler {
 		@Override
 		public void handle(Signal signal) {
 			LOG.error("RECEIVED SIGNAL " + signal.getNumber() + ": SIG" + signal.getName());
+			LOG.error("This JVM will shut down because it was killed from the outside.");
 			prevHandler.handle(signal);
 		}
 	}

flink-runtime/src/main/scala/org/apache/flink/runtime/jobmanager/JobManager.scala

@@ -1382,6 +1382,7 @@ object JobManager {
     // startup checks and logging
     EnvironmentInformation.logEnvironmentInfo(LOG.logger, "JobManager", args)
     EnvironmentInformation.checkJavaVersion()
+    SignalHandler.register(LOG.logger)
 
     // parsing the command line arguments
     val (configuration: Configuration,

flink-runtime/src/main/scala/org/apache/flink/runtime/taskmanager/TaskManager.scala

@@ -64,7 +64,7 @@ import org.apache.flink.util.NetUtils
 import org.apache.flink.runtime.process.ProcessReaper
 import org.apache.flink.runtime.security.SecurityUtils
 import org.apache.flink.runtime.security.SecurityUtils.FlinkSecuredRunner
-import org.apache.flink.runtime.util.{LeaderRetrievalUtils, MathUtils, EnvironmentInformation}
+import org.apache.flink.runtime.util.{SignalHandler, LeaderRetrievalUtils, MathUtils, EnvironmentInformation}
 
 import scala.concurrent._
 import scala.concurrent.duration._
@@ -1204,6 +1204,7 @@ object TaskManager {
     // startup checks and logging
     EnvironmentInformation.logEnvironmentInfo(LOG.logger, "TaskManager", args)
     EnvironmentInformation.checkJavaVersion()
+    SignalHandler.register(LOG.logger)
 
     val maxOpenFileHandles = EnvironmentInformation.getOpenFileHandlesLimit()
     if (maxOpenFileHandles != -1) {