improvement for February training 'ewoksfordevs'

• we need to split the training to have one speaker in the morning and one in the afternoon
• maybe the training should be split
  • ewoks integration can be another training (online processing execution can be moved to another training or presented as a demo at least. There is no time for the last part and especially it could be a one hour exercise)
  • maybe two half a day would be better
• Maybe a deeper presentation of the trainer and get interest of the trainees could bring something. Breaking the ice kind of * slide 17: provide a default value on the slide
• link names 'source_output' and 'target_input' are confusing for some users. Maybe it could be simplified
• maybe another example than add / sum can be found for the tutorial (like multiplication...)
• discover task: it now expect the python module. Which is confusing for some people which try to provide a file path. It would be nice to add an error message if a path with containing '/' or ending by .py is provided. OR get some red background when the '/' character is provided
• slide 73: the interface from python is not very clear to user. We could provide a clearer example for future = submit(args=args, kwargs=kwargs) !22 (merged)