Add support for running CodeOcean under a subpath

* Also refactor (JavaScript) routes

app/assets/javascripts/editor/editor.js.erb

@@ -1,7 +1,7 @@
 var CodeOceanEditor = {
     //ACE-Editor-Path
     // ruby part adds the relative_url_root, if it is set.
-    ACE_FILES_PATH: '<%= (defined? Rails.application.config.relative_url_root) && Rails.application.config.relative_url_root != nil && Rails.application.config.relative_url_root != "" ? Rails.application.config.relative_url_root : "" %>' + '/assets/ace/',
+    ACE_FILES_PATH: '<%= "#{Rails.application.config.relative_url_root.chomp('/')}/assets/ace/" %>',
     THEME: 'ace/theme/textmate',
 
     //Color-Encoding for Percentages in Progress Bars (For submissions)

app/assets/javascripts/editor/participantsupport.js.erb

@@ -142,7 +142,7 @@ CodeOceanEditorRequestForComments = {
     var createRequestForComments = function (submission) {
       $.ajax({
         method: 'POST',
-        url: '/request_for_comments',
+        url: Routes.request_for_comments_path(),
         data: {
           request_for_comment: {
             exercise_id: exercise_id,