translations: Chinese(zh) translations by Shuyu Wang aka andelf
(cherry picked from commit 9d34e9e886918159404ba4bfa14838b73920e5b7)
mod_translation: Add zh to languages list, add Shuyu Wang to translators

Fixes #498
(cherry picked from commit 876d2b6de88176edb25d9e04a69976c8231fe1c9)