Merge pull request #495 from goldrush/develop

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Merge pull request #499 from goldrush/develop

Develop
Merge pull request #501 from goldrush/develop

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show_starsメソッドがかぶっていた。
Merge pull request #504 from goldrush/develop

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Merge pull request #505 from goldrush/master

本番サーバーでの修正を逆マージ