Translate all documents into Japanese

[sizer]

• [x] README.md
• [ ] SUMMARY.md
• [x] getting-started.md
• [x] application-structure.md
• [x] the-client.md
• [x] routing.md
• [x] main-menu.md
• [x] dashboard.md
• [ ] css-in-scala.md
• [ ] integrating-javascript-components.md
• [ ] todo-module-and-data-flow.md
• [x] autowire-and-boopickle.md
• [x] server-side.md
• [ ] testing.md
• [ ] debugging.md
• [ ] logging.md
• [ ] sbt-build-definition.md
• [ ] using-resources-from-webjars.md
• [ ] production-build.md
• [ ] faq.md
• [ ] what-next.md