pgAdmin4 Chinese (Simplified) translation Patch

Hi all,
    i've done the chinese (Simplified) transation of pgadmin4, and the attachment is the patch, hope to add the mainline.
   
    Does I need do 'pybabel compile -d web/pgadmin/translations' to generate the catalogues can be used, i have not generate it yet,
    if it is needed, i will add it the next time.

Regards,
-- 
tingting hui
https://my.oschina.net/innovation