Renaming jenkins job templates to be more understandable on their purposes.

- Renaming 'config-layout' job to 'zuul-layout', to be more specific, because this jobs is to validate the zuul layout file and the config-layout didnt says too much.
- Renaming 'tutorials' for 'flake8'.

Change-Id: I155e168ed241e3b430b5a9359da45225975aad2a