unit analytics
Merge branch 'master' of https://github.com/kontur-edu/uLearn

Conflicts:
	src/uLearn.Web/Views/SlideNavigation/TableOfContents.cshtml
	src/uLearn.Web/uLearn.Web.csproj
Unit statistics + group changer for instructors
Merge branch 'master' of https://github.com/kontur-edu/uLearn

Conflicts:
	src/uLearn.Web/Content/ulearn.css