Reuse disable_rollback on stack update

If disable_rollback API parameter is not supplied to stack update,
use corresponding value of existing stack.

Change-Id: Iad60e12d31dc3850071dc0b8562c7b99f53adba4
Closes-Bug: #1324366
Only delete stack user project from correct domain

Check the domain ID for the project matches the configured domain from
heat.conf, so we avoid the bad outcome of deleting the user's project
when heat has been configured for stack domain users after creating
some stacks.

Change-Id: I247e732033f44daf0de5b0efeff6c263814d13ab
Closes-Bug: #1365332
Merge "Reuse disable_rollback on stack update"
Merge "Only delete stack user project from correct domain"