Add Simple Chinese translation

Hi,
I'm  glad to use anchor-cms,but it does not have Simple Chinese translation,I followed the documentation on [http://anchorcms.com](http://anchorcms.com/docs/getting-started/configuration) and add the Simple Chinese translation files,and also followed the [ISO 639 'underscore' ISO 3166](http://www.localeplanet.com/icu/) format.

I hope you can merge  it to the main branch, please let me know if have any problem
Thank you.