Enhance DescribeStacks. Keep track of deleted stacks. Stack status.

Made describe_stacks more in line with http://docs.aws.amazon.com/AWSCloudFormation/latest/APIReference/API_DescribeStackResource.html
Merge pull request #239 from joekiller/enhance/describe_stacks_delete_stacks_stack_status

Enhance DescribeStacks. Keep track of deleted stacks. Stack status.