Adding Sidney Zhang to Contributors

Thanks to Sidney Zhang. He has contributed with German translation.
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Initial support for dir=rtl
Using form.data instead of self.get_argument
Using WTForms for validate search posts
Unnecesary passing options
Improved form submission using CommentForm
Unified message template using MessageModule
Comment edition using WTForms #17
Moving reference form forms module to handlers module
Creating base module
Moving handlers & ui_modules modules into web module