the assumption that the hostname in EC2 is no longer right and the URL to get public dns has changed
the ip parameter in startJettyServer is not used..remove it
change the address to get public hostname in ec2
add SPARK_PUBLIC_DNS and SPARK_IAAS_NAME env variable to fix support for ec2 deployment
remove ec2-specific code but keep the comments about SPARK_PUBLIC_DNS in spark-env.sh.template