Allow author of a training to view the list of trainee, and their report or progress.

[leefurong]

I have created a training for c++ beginners. I would love to see who is enrolling my training, and view their progress. That will help me understand what is happening, and hence provide appropriate support for them.

Here is the training I created: https://vijos.org/d/zenkids01/training/5e140027f41362acda1408be

[undefined-moe]

We suggest using homework instead of training in this case.