workflow: CWL example
Prepare CWL workflow example for this demo analysis.
We can keep both Yadage and CWL workflows in the same repository, and users would be able to choose the workflow specification by altering the REANA spec file. (after https://github.com/reanahub/reana-client/issues/10 is implemented)
Alternatively, we could have different repositories for different workflow engines, but I think it's better to keep the number of repositories low...
(see also https://github.com/reanahub/reana-demo-worldpopulation/issues/9)