[SPARK-11218][CORE] show help messages for start-slave and start-master

Addressing https://issues.apache.org/jira/browse/SPARK-11218, mostly copied start-thriftserver.sh.
```
charlesyeh-mbp:spark charlesyeh$ ./sbin/start-master.sh --help
Usage: Master [options]

Options:
  -i HOST, --ip HOST     Hostname to listen on (deprecated, please use --host or -h)
  -h HOST, --host HOST   Hostname to listen on
  -p PORT, --port PORT   Port to listen on (default: 7077)
  --webui-port PORT      Port for web UI (default: 8080)
  --properties-file FILE Path to a custom Spark properties file.
                         Default is conf/spark-defaults.conf.
```
```
charlesyeh-mbp:spark charlesyeh$ ./sbin/start-slave.sh
Usage: Worker [options] <master>

Master must be a URL of the form spark://hostname:port

Options:
  -c CORES, --cores CORES  Number of cores to use
  -m MEM, --memory MEM     Amount of memory to use (e.g. 1000M, 2G)
  -d DIR, --work-dir DIR   Directory to run apps in (default: SPARK_HOME/work)
  -i HOST, --ip IP         Hostname to listen on (deprecated, please use --host or -h)
  -h HOST, --host HOST     Hostname to listen on
  -p PORT, --port PORT     Port to listen on (default: random)
  --webui-port PORT        Port for web UI (default: 8081)
  --properties-file FILE   Path to a custom Spark properties file.
                           Default is conf/spark-defaults.conf.
```

Author: Charles Yeh <[email protected]>

Closes #9432 from CharlesYeh/helpmsg.

Author: Charles Yeh

sbin/start-master.sh

@@ -23,14 +23,28 @@ if [ -z "${SPARK_HOME}" ]; then
   export SPARK_HOME="$(cd "`dirname "$0"`"/..; pwd)"
 fi
 
+# NOTE: This exact class name is matched downstream by SparkSubmit.
+# Any changes need to be reflected there.
+CLASS="org.apache.spark.deploy.master.Master"
+
+if [[ "$@" = *--help ]] || [[ "$@" = *-h ]]; then
+  echo "Usage: ./sbin/start-master.sh [options]"
+  pattern="Usage:"
+  pattern+="\|Using Spark's default log4j profile:"
+  pattern+="\|Registered signal handlers for"
+
+  "${SPARK_HOME}"/bin/spark-class $CLASS --help 2>&1 | grep -v "$pattern" 1>&2
+  exit 1
+fi
+
 ORIGINAL_ARGS="$@"
 
 START_TACHYON=false
 
 while (( "$#" )); do
 case $1 in
     --with-tachyon)
-      if [ ! -e "$sbin"/../tachyon/bin/tachyon ]; then
+      if [ ! -e "${SPARK_HOME}"/tachyon/bin/tachyon ]; then
         echo "Error: --with-tachyon specified, but tachyon not found."
         exit -1
       fi
@@ -56,12 +70,12 @@ if [ "$SPARK_MASTER_WEBUI_PORT" = "" ]; then
   SPARK_MASTER_WEBUI_PORT=8080
 fi
 
-"${SPARK_HOME}/sbin"/spark-daemon.sh start org.apache.spark.deploy.master.Master 1 \
+"${SPARK_HOME}/sbin"/spark-daemon.sh start $CLASS 1 \
   --ip $SPARK_MASTER_IP --port $SPARK_MASTER_PORT --webui-port $SPARK_MASTER_WEBUI_PORT \
   $ORIGINAL_ARGS
 
 if [ "$START_TACHYON" == "true" ]; then
-  "${SPARK_HOME}/sbin"/../tachyon/bin/tachyon bootstrap-conf $SPARK_MASTER_IP
-  "${SPARK_HOME}/sbin"/../tachyon/bin/tachyon format -s
-  "${SPARK_HOME}/sbin"/../tachyon/bin/tachyon-start.sh master
+  "${SPARK_HOME}"/tachyon/bin/tachyon bootstrap-conf $SPARK_MASTER_IP
+  "${SPARK_HOME}"/tachyon/bin/tachyon format -s
+  "${SPARK_HOME}"/tachyon/bin/tachyon-start.sh master
 fi

sbin/start-slave.sh

@@ -31,18 +31,24 @@
 #                           worker.  Subsequent workers will increment this
 #                           number.  Default is 8081.
 
-usage="Usage: start-slave.sh <spark-master-URL> where <spark-master-URL> is like spark://localhost:7077"
-
-if [ $# -lt 1 ]; then
-  echo $usage
-  echo Called as start-slave.sh $*
-  exit 1
-fi
-
 if [ -z "${SPARK_HOME}" ]; then
   export SPARK_HOME="$(cd "`dirname "$0"`"/..; pwd)"
 fi
 
+# NOTE: This exact class name is matched downstream by SparkSubmit.
+# Any changes need to be reflected there.
+CLASS="org.apache.spark.deploy.worker.Worker"
+
+if [[ $# -lt 1 ]] || [[ "$@" = *--help ]] || [[ "$@" = *-h ]]; then
+  echo "Usage: ./sbin/start-slave.sh [options] <master>"
+  pattern="Usage:"
+  pattern+="\|Using Spark's default log4j profile:"
+  pattern+="\|Registered signal handlers for"
+
+  "${SPARK_HOME}"/bin/spark-class $CLASS --help 2>&1 | grep -v "$pattern" 1>&2
+  exit 1
+fi
+
 . "${SPARK_HOME}/sbin/spark-config.sh"
 
 . "${SPARK_HOME}/bin/load-spark-env.sh"
@@ -72,7 +78,7 @@ function start_instance {
   fi
   WEBUI_PORT=$(( $SPARK_WORKER_WEBUI_PORT + $WORKER_NUM - 1 ))
 
-  "${SPARK_HOME}/sbin"/spark-daemon.sh start org.apache.spark.deploy.worker.Worker $WORKER_NUM \
+  "${SPARK_HOME}/sbin"/spark-daemon.sh start $CLASS $WORKER_NUM \
      --webui-port "$WEBUI_PORT" $PORT_FLAG $PORT_NUM $MASTER "$@"
 }