Adding the translation for zh_cn.

Change-Id: I2d8b8f9b4ce5a1818955ee6c9ccd53a16f594187
Reviewed-by: Niels Weber <niels.weber@digia.com>
Reviewed-by: Karsten Heimrich <karsten.heimrich@digia.com>
Reviewed-by: Tim Jenssen <tim.jenssen@digia.com>