Add failing test for #243.

test/erlydtl_test_defs.erl

@@ -736,6 +736,9 @@ all_test_defs() ->
        {"|join:\", \" (binary)",
         <<"{{ var1|join:\", \" }}">>, [{var1, [<<"Liberte">>, "Egalite", <<"Fraternite">>]}],
         <<"Liberte, Egalite, Fraternite">>},
+       {"|join:\", \" (numbers)",
+        <<"{{ var1|join:\", \" }}">>, [{var1, [1, 2, 3]}],
+        <<"1, 2, 3">>},
        {"|last",
         <<"{{ var1|last }}">>, [{var1, "XYZ"}],
         <<"Z">>},