Enable Coverity Scan integration

Now that the ci PR was merged, we can enable Coverity Scan integration. As admin of the repository you will need to go to scan.coverity.com and sign in with your github account, and do "Add Project" -> "Register my GitHub Project" -> select the boostorg/program_options project to add. After that, you need to take the project token on the project settings page and put it into your Travis CI settings for the boostorg/program_options builds, and make them private (there's a toggle):

COVERITY_SCAN_TOKEN (set to the token from coverity scan)
COVERITY_SCAN_NOTIFICATION_EMAIL (set to your email so you get notified on completed builds)

At some point I might put together some better instructions on how to do this with pictures...

Also recommend setting up a weekly cron on develop and master in travis CI.

まず boostorg/program_options の Coverity Scan プロジェクト登録手順に従い、次にプロジェクトの Travis CI 設定を確認します。Coverity トークンと通知メールが設定され、ビルドが非公開で、develop と master に対して週次の cron ジョブが設定されていれば完了です。

索引モデルが issue の本文から書いたものです。