js: workaround to avoid <option> tags inside <script>

The naive formencode html parser would sometimes (Python 2.6?) fail with
  AssertionError: <option> outside of <select>

kallithea/templates/base/base.html

@@ -271,7 +271,7 b''
               });
           } else if (context == 'changelog') {
               if (e.choice.type == 'tag' || e.choice.type == 'book') {
-                  $("#branch_filter").append($('<option/>').val(e.choice.text));
+                  $("#branch_filter").append($('<'+'option/>').val(e.choice.text));
               }
               $("#branch_filter").val(e.choice.text).change();
           } else {

kallithea/templates/pullrequests/pullrequest.html

@@ -134,7 +134,7 b''
                 var length = options.length;
                 for(var j = 0; j < length; j++)
                 {
-                  $optgroup.append($('<option/>').text(options[j][1]).val(options[j][0]));
+                  $optgroup.append($('<'+'option/>').text(options[j][1]).val(options[j][0]));
                 }
                 $other_ref.append($optgroup);
               }