When we moved parameters from the stack table to the template table
we did it in a "flexible" way, but this led to some difficult to
diagnose problems. So this patch totally removes "env" as an argument
to the Stack class to make absolutely sure that we are doing this
correctly. I came across these bugs when rebasing decouple-nested.
- env was not getting passed into instance group make_templates()
- template deepcopy was not working correctly (causing some problems
when deleting backup stacks)
Change-Id: I85cfb01c68ff5a44e2ff4f6e446870efb7205933
e3950a4e72