isso: js: embed: Insert Postbox before comments

This is a backport of isso-comments#820 to the 0.12.6 release branch.

This restores the behavior before isso-comments#311

Closes isso-comments#815

Note: This is only a hotfix!

isso/js/embed.js

@@ -70,7 +70,7 @@ require(["app/lib/ready", "app/config", "app/i18n", "app/api", "app/isso", "app/
                 }
 
                 // Finally, create Postbox with configs fetched from server
-                isso_thread.append(new isso.Postbox(null));
+                $('#isso-root').prepend(new isso.Postbox(null));
 
                 if (rv.total_replies === 0) {
                     heading.textContent = i18n.translate("no-comments");