Added script for launching Spark on EC2 from Mesos, to make it easier

for new users to get up and running on EC2.

ec2/README

+This folder contains a script, spark-ec2, for launching Spark clusters on
+Amazon EC2. Usage instructions are available online at:
+
+https://github.com/mesos/spark/wiki/Running-Spark-on-Amazon-EC2

ec2/deploy.generic/root/mesos-ec2/ec2-variables.sh

+#!/bin/bash
+
+# These variables are automatically filled in by the mesos-ec2 script.
+export MESOS_MASTERS="{{master_list}}"
+export MESOS_SLAVES="{{slave_list}}"
+export MESOS_ZOO_LIST="{{zoo_list}}"
+export MESOS_HDFS_DATA_DIRS="{{hdfs_data_dirs}}"
+export MESOS_MAPRED_LOCAL_DIRS="{{mapred_local_dirs}}"

ec2/spark-ec2

+#!/bin/sh
+
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+# 
+#     http://www.apache.org/licenses/LICENSE-2.0
+# 
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+cd "`dirname $0`"
+PYTHONPATH="./third_party/boto-2.4.1.zip/boto-2.4.1:$PYTHONPATH" python ./spark_ec2.py $@