Adds a new nested stack deployment which allows operators to
opt-in to deploy tarball's and RPM packages by setting
DeployArtifactURLs as a parameter_default in a Heat
environment.
The intent is to use this setting to allow t-h-t to
transparently deploy things like tarballs of puppet modules
via a Swift Temp URL.
Change-Id: I1bad4a4a79cf297f5b6e439e0657269738b5f326
Implements: blueprint puppet-modules-deployment-via-swift
55054f02d7