Start japanese (ja) translation
Translate index.html; fix _config.yml
Translate installation/index.md
Translate installation/mac.md
Translate installation/windows.md
Translate installation/linux.md
Translate installation/deploy.md
Translate installation/upgrading.md
Translate installation/troubleshooting.md
Fix installation/troubleshooting.md - long lines
Update YAML front matter for other pages
Merge pull request #1634 from chibicode/gh-pages

[Translations: /ja] Japanese translation
Minor update to wording

Document refers to a different file than the one the user has been shown to download.
Merge pull request #1682 from mfeckie/patch-2

Minor update to wording
Add language switcher to the top
Merge pull request #1684 from chibicode/better-language-dropdown

[Docs] Add language switcher to the navbar
Translate the rest of japanese doc
Changes per 582b6e8
Improve translation on markdown
Fix curl command in german docs.