Reference alerts by id

[miguelgdoval]

When having to deal with many services, we'd need a way to also have many types of alerts (configured ad hoc for each of them).
I think it would be great to reference each alert definition with an id, that will be used by the services to know which alert they shuld trigger.
The schema would be something like this:
alerting:
custom:
id: "alert1"
...
custom:
id: "alert2"
...
services:

• name: service1
  alerts:
  • type: custom
    id: "alert1"
    ...
• name: service2
  alerts:
  • type: custom
    id: "alert2"
    ...

[TwiN]

Hello @miguelgdoval,

See #96 -- it's not exactly a duplicate, but whatever solution comes out of that issue will likely solve this issue.