Revert "Merge pull request #1478 from opf/feature/with-angular-busy"

This reverts commit b46e5405288c621aabf1c3bdbb102ba3b4b4691f, reversing
changes made to aed28723f2616f26484fcafeaa6c468a94dc0e1a.

Conflicts:
	app/assets/javascripts/angular/openproject-app.js