Integrate EC2 C3 instance types

This initial commit addresses #229 as such, making the [New Generation of EC2 Instances for Compute-Intensive Workloads](http://aws.typepad.com/aws/2013/11/a-generation-of-ec2-instances-for-compute-intensive-workloads.html) available for use (likewise the [New G2 Instance Type](http://aws.typepad.com/aws/2013/11/build-3d-streaming-applications-with-ec2s-new-g2-instance-type.html)).

I'll propose related cluster configuration changes via a subsequent commit.