add ja/models/data-validation.rst
[zh_CN] done /zh/development.rst
Merge pull request #1971 from blackpuppy/zh

[zh_CN] done /zh/development.rst
Merge pull request #1964 from hotta/add_data_validation

add ja/models/data-validation.rst
[zh_CN] done /zh/models/additional-methods-and-properties.rst
Merge pull request #1973 from blackpuppy/zh

[zh_CN] done /zh/models/additional-methods-and-properties.rst