Fix HTML5 Weekly broken image with updated twitter avatar
Add Japanese translation (contents/jp/**/*.md)

- Add contents/jp/**/*.md
-- Only contents/jp/mentions/*.md were translated.
-- contents/jp/*.md and build/src/index.html have yet to be taken care of in the newx few days.
Merge pull request #86 from YasuhiroYoshida/develop

Add Japanese translation (contents/jp/**/*.md)
Add Japanese translation (contents/jp)
Add Japanese page link
Merge pull request #87 from YasuhiroYoshida/develop

Add Japanese translation (contents/jp/*.md and link)
Merge pull request #81 from krisbulman/patch-1

Fix HTML5 Weekly broken image with updated twitter avatar
Add Japan flags.