ACE Editor: Restore custom annotations

This is a regression introduced by the recent ACE editor update to 1.2.0 and 1.2.9. We should consider this change when working https://github.com/openHPI/codeocean/issues/250.

vendor/assets/javascripts/ace/ace.js

@@ -14819,6 +14819,8 @@ var Gutter = function(parentEl) {
                 rowInfo.className = " ace_warning";
             else if (type == "info" && (!rowInfo.className))
                 rowInfo.className = " ace_info";
+            else if (!!!type && annotation.className)
+                rowInfo.className = " " + annotation.className
         }
     };