[Z-Push] Owncloud doesnt't support CARDDAV_SUPPORTS_SYNC, 

so set it to false and `carddav` sync works again.

```
define('CARDDAV_SUPPORTS_SYNC', false);

If the CardDAV server supports the "sync-collection" operation.

    DAViCal supports it, and it's faster, so set it to true if that's your server.

    SabreDav, Owncloud and SOGo don't support it, so set it to false.
```
see [Wiki](https://github.com/fmbiete/Z-Push-contrib/wiki/Example-Configuration)