Telegram(plugin/contrib) issue 309 (#1221)
Telegram(plugin/contrib) issue 309 (#1221)

* telegram webhook: https://github.com/alerta/alerta-contrib/issues/309,
create blackout from alert_id (/blackout <alert_id>).

* telegram webhook: backward compatability: Try to parse alert_id from
/ack command. send_message_reply needs/uses alert.id so we can't just
parse /blackout environment|resource|event. This is ugly hack and should be
removed after grace period/telegram(PLUGIN) sends /blackout with alert_id.
guardian/alerta,guardian/alerta,guardian/alerta,guardian/alerta