Dump individual recipe contents

Opening regarding @vmiheer's comment in #701:

> On other hand, is there way to keep the generated shebang script for later inspection? I see a file created in /tmp/justJOLujt/maestro but it gets deleted when the just execution stops. Maybe printing the path at the beginning so that one can put sleep 100 to inspect the content would be useful.

This is definitely possible, but an easier way of doing it might just be to add the ability to just print the generated shebang script to stdout. Would that work?