v1.0.4 Updates to Auto Scaling Group, EMR and new ECS workshop

Auto Scaling with Multiple instances changes:

• Update EC2 Auto Scaling with multiple instance types and purchasing options best practices, leaving custom interruption handler as an optional exercise to suit other use cases where Capacity Rebalancing may not be the best fit (e.g. queue workers) - #134
  Update EKS Metric Server and rest of dependencies
• Update workshop weights to position the short version first and Running EC2 Workloads at scale at the bottom, as this is a shorter version that's preferable for Spot-only (and remote) events.
• Update to AWS CLI 2.x

EMR Changes

• Modify screenshot for Instance fleets to include the allocation strategy
• Add a step to remove AWS CLI 1.x before installing AWS CLI 2.x
• Add instructions for SSH tunneling via Cloud9

ECS Workshop

• New ECS workshop covering ECS Capacity Providers, EC2 Spot and Fargate Spot best practices and ECS Cluster Autoscaler (CAS)