Revert hybrid app of AngularJs (1) and Angular (4)

It turns out that combining AngularJs and Angular in one application (a.k.a. "hybrid app") does not work well. It slows down development because it introduces lots of complexity: services that are used by both frameworks need to be up- and/or downgraded, Material 1 + 2 together introduces hard-to-fix bugs, etc. And there's not much info online about fixing it.

We therefore revert the usage of Angular in the Channel Manager for now, and go back to AngularJs only. The plan is to first wrap up planned features in AngularJs, and then upgrade the whole Channel Manager to Angular as one big focused effort.