Allow adding many workflows with the same name.
The way this works is by adding the new workflows under another
namespace.
Notice that:
1. Namespaces are not part of the mistral DSL.
2. When executing a workflow, the namespace passes down to the
subworkflow.
3. When searching for the sub-workflow definition -
If no workflow was found in the given namespace, than the defualt
namespace will be used.
4. The default namespace is an empty string.
5. The namespace property or the workflow execution will be under
params
Partially-Implements: blueprint create-and-run-workflows-within-a-namespace
Change-Id: Id248ec5906a0899d188675d002b45f6249d36d90
cbee740de5