jpnews: Add news for github pages migration
plugins: raise an error based on exist code
travis: Do not push via pull request
jpmain: Update how to ask us to review
jpnews: Add a link to how to submit news
plugins: Do validation using xmllint
make xmllint happy
jpmain: Add gentoojp-github-pages
jpmain: Add a link to gentoojp-github-pages
jpmain: Update the description about news submission
Merge pull request #2 from nabeken/update-for-github-pages

Update for github pages