This commit adds support for Grafana's new alerting system, Grafana
Alerting. The existing Grafana integration has been modified to
detect the version of the notification through the structure of the
payload body, since the the structure varies by version. Support for
legacy alerting is been continued. Example fixtures have been added
for Grafana Alerting's webhooks.
Tests updated.
Having the alert state in the message body is useful when alert topics
are not defined by alert description but encoded in the url.
E.g. in large environments having a topic for each alert [alerting] and [ok] would
make it harder to properly track if an alert has been resolved.
When each alert is in a single topic, so far, the alert state has been missing.
This change will add the current alert state and a fitting icon in front
of the alert name.(Similar to the prometheus alertmanager integration)
The test cases have been amended to cover all possible alert states, even
though realistically grafana only fires the ok and alerting states via
webhook.
Hari Prashant Bhimaraju
AdamVB
Jenny Ghose