Collect and view statistics on the number of downloads and the number of clicks on each presentation

[Andrenux]

The statistics should be available to the course director (in manage presentations or other statistics tab).

[pavelsokolov]

These starts are needed by the Intelligent Feedback app:

• total views
• coverage (percent watched)
• time watched

[orkit]

The number of clicks and downloads is summed and displayed in the map / list / table video layout in Manage view. By clicking on the statistics icons, you end up in a view where more information in the future can be displayed.

[orkit]

Implemented.