[scripts] Update error message for missing commands of the jobmanager…

….sh script

flink-dist/src/main/flink-bin/bin/jobmanager.sh

@@ -79,7 +79,7 @@ case $STARTSTOP in
  rotateLogFile $log
  rotateLogFile $out
 
- echo Starting job manager
+ echo "Starting Job Manager"
  $JAVA_RUN $JVM_ARGS ${FLINK_ENV_JAVA_OPTS} "${log_setting[@]}" -classpath "`manglePathList "$FLINK_JM_CLASSPATH:$INTERNAL_HADOOP_CLASSPATHS"`" org.apache.flink.runtime.jobmanager.JobManager --executionMode $EXECUTIONMODE --configDir "$FLINK_CONF_DIR" > "$out" 2>&1 < /dev/null &
  echo $! > $pid
 
@@ -88,18 +88,18 @@ case $STARTSTOP in
  (stop)
  if [ -f $pid ]; then
  if kill -0 `cat $pid` > /dev/null 2>&1; then
- echo Stopping job manager
+ echo "Stopping job manager"
  kill `cat $pid`
  else
- echo No job manager to stop
+ echo "No job manager to stop"
  fi
  else
- echo No job manager to stop
+ echo "No job manager to stop"
  fi
  ;;
 
  (*)
- echo Please specify start or stop
+ echo "Please specify 'start (cluster|local)' or stop"
  ;;
 
 esac