Merge pull request #3594 from edx/christina/delete-dead-files

These files are not being used.

cms/static/js/collections/course_relative.js

-define(["backbone", "js/models/course_relative"], function(Backbone, CourseRelativeModel) {
-    var CourseRelativeCollection = Backbone.Collection.extend({
-        model: CourseRelativeModel
-    });
-    return CourseRelativeCollection;
-});

cms/static/js/models/course_relative.js

-define(["backbone"], function(Backbone) {
-    var CourseRelative = Backbone.Model.extend({
-        defaults: {
-            course_location : null, // must never be null, but here to doc the field
-            idx : null  // the index making it unique in the containing collection (no implied sort)
-        }
-    });
-    return CourseRelative;
-});