[enh] add translatable strings to javascript - closes #461

searx/static/themes/simple/js/searx.js

@@ -1314,7 +1314,7 @@ module.exports = AutoComplete;
           })
           .catch(function() {
             result_table_loadicon.classList.remove('invisible');
-            result_table_loadicon.innerHTML = "could not load data!";
+            result_table_loadicon.innerHTML = could_not_load;
           });
         }
       }