feat(calendar): validate org defaults in calendar.settings

Documented keys default_location, default_duration_minutes,
default_recurrence; unknown keys (week_patterns) passthrough;
invalid known shape returns 400.

Refs EventHub/EventHubBack#63

src/handlers/handler_calendar_by_id.erl

@@ -154,6 +154,9 @@ update_calendar(Req) ->
               handler_utils:send_error(Req2, 402, <<"Subscription required for commercial calendar">>);
             {error, not_found} ->
               handler_utils:send_error(Req2, 404, <<"Calendar not found">>);
+            {error, {invalid_settings, Key}} when is_binary(Key) ->
+              handler_utils:send_error(Req2, 400,
+                <<"Invalid settings.", Key/binary>>);
             {error, _} ->
               handler_utils:send_error(Req2, 500, <<"Internal server error">>)
           end;