Delete a stack without deleting the resources

This blueprint is partnered with blueprint adopt-stack to allow stacks to be moved from one heat instance to another in a 2 step process:
* a stack is abandoned, deleting the stack but leaving the resources running
* the state returned from the abandon action is used to do a stack adopt. This creates a stack which adopts the passed resources, and does not create any new resources

This blueprint may be useful on its own for users who want to use heat to use heat to invoke openstack resources but don't want to use heat to manage those resources.

Abandoning a stack would do the following:
* Collect all the resource state (resource IDs, resource data, metadata?)
* Delete the stack with DeletionPolicy on all resources overridden to 'Retain'
* Return a json structure to the user containing the abandoned template, plus the resource state

The json structure will be in a format that can be consumed by blueprint adopt-stack