Sync-up with CloudFormation

• Switches the Lambda to use Docker images instead of files stored in S3. This defaults to the stable images available on the AWS Marketplace, but custom images can be built locally as per the AutoSpotting build instructions.
• This also enables AutoSpotting be deployed in any region without having regional S3 buckets previously required because of to the dependency between Lambda and S3.
• Additional variables have been introduced, which expose some recent features, in particular the EBS storage upgrade for volumes smaller than 170GB.