Notify maintainer when a repo master build has failed for a prolonged period

For a less popular repo, the master build could be in failed state for prolonged period without being noticed.

E.g. [a 25 day failure here](https://travis-ci.org/ManageIQ/manageiq-providers-foreman/builds). This build failure is caused by a core change and we should have caught and fixed this problem early on vs now being notified by a bug report.

So a feature request: miq-bot to notify (e.g. by emailing) maintainers after say `failure not fixed within 1 day`.

The issue does not name files, tests, or an entry point. Start by locating miq-bot's handling of repository build status and maintainer notifications, then determine how a failure's duration is tracked and where a one-day threshold and email behavior should be specified.

Written by the indexing model from the issue text.