Slight improvement in logging for Rexfile compilation errors
Sleep up to 8 seconds before querying instance list following new instance creation

Pass parameters into Amazon's list_instances routine to allow filtering
Implement listing/creating AMIs (server images) in Rex::Cloud::Amazon
Handle single 'Error' elements in Amazon responses as well as lists of Errors
Clean up get/create_cloud_image(s) code
Add basic support for Amazon autoscaling groups
Add basic support for Amazon launch configurations