Heat used to accept either stack name or id
Scale nodes in the documentation and in the argparse usage
states that stacks can be identified by name or id but mistral
only accepts stack names.
This makes the client accept names or ids and pass names for the
mistral workflow
Change-Id: If7527e36c1e5d2214dc155392a2e3750b38ec365
Closes-Bug: #1640933