An option to ignore pings when a check is paused

[cuu508]

Use case: you have a a misbehaving service that sporadically sends pings to Healthchecks. You've acknowledged the issue and are working on solution but in meantime don't want to receive continuous alerts about the service going up and down.

There is an existing "Pause" function, but it has a shortcoming: when a paused check receives a ping it gets "unpaused", and you start receiving notification again. There was a discussion on this in #343.

One potential solution would be allowing users to opt in to a different "paused" state behavior:

If a check is paused, and "Ignore pings, stay in paused state" is selected, then:

• pings from the misbehaving service get logged but don't change check's status – it stays paused
• since the check is paused, it doesn't show as red in the dashboard
• since the check is paused, it does not trigger the "Reminder: 1 check still down" reminders if these are enabled