More jshint errors

https://trello.com/c/JuoHRCmt/93-more-jshint-errors

Go through the jshint code and audit all error message it is able to generate. Integrate all that are useful to us.

The mappings for jshint errors live here; the validation tests live here (though check the other language validation tests, which are more robust, for inspiration). The translation file that generates the error messages is here.

首先，根据 JSHint 能够生成的错误，审查 src/validations/javascript/jshint.js 中的 JSHint 映射。阅读 src/validations/javascript.js 中的验证测试，并将其与其他语言的验证测试进行比较，然后更新 locales/en.json 中相关的条目。完成标准是：有用的 JSHint 错误已集成，并由验证测试覆盖。