Initialize connection to EMR
options parameter must include values for :aws_access_key_id and :aws_secret_access_key in order to create a connection
emr = EMR.new( :aws_access_key_id => your_aws_access_key_id, :aws_secret_access_key => your_aws_secret_access_key )
adds an instance group to a running cluster docs.amazonwebservices.com/ElasticMapReduce/latest/API/API_AddInstanceGroups.html
adds new steps to a running job flow. docs.amazonwebservices.com/ElasticMapReduce/latest/API/API_AddJobFlowSteps.html
returns a list of job flows that match all of the supplied parameters. docs.amazonwebservices.com/ElasticMapReduce/latest/API/API_DescribeJobFlows.html
modifies the number of nodes and configuration settings of an instance group.. docs.amazonwebservices.com/ElasticMapReduce/latest/API/API_ModifyInstanceGroups.html
creates and starts running a new job flow docs.amazonwebservices.com/ElasticMapReduce/latest/API/API_RunJobFlow.html
locks a job flow so the Amazon EC2 instances in the cluster cannot be terminated by user intervention. docs.amazonwebservices.com/ElasticMapReduce/latest/API/API_SetTerminationProtection.html
shuts a list of job flows down. docs.amazonwebservices.com/ElasticMapReduce/latest/API/API_TerminateJobFlows.html