Getting the old 0.7 Spark when running remote

[akeed]

When doing: git clone git://github.com/amplab/training-script.git -b ampcamp4 I get the old training material, including images.

spark_ec2.py seems to be hard coded against ampcamp 3 ami:

A static URL from which to figure out the latest Mesos EC2 AMI

LATEST_AMI_URL = "http://s3.amazonaws.com/ampcamp-amis/latest-ampcamp3"