Discord webhook notifier

configuration.yaml

notify discord_webhook:
  - name: discord_webhook
    platform: rest
    method: POST
    message_param_name: content
    title_param_name: username
    data:
      username: Home Assistant
    resource: "https://discordapp.com/api/webhooks/36723429/UBbENaEKpuUHOWs3wBjAiq2Ribcf74688fcn6n8748M9y0p7KD7C-YJ"

Service data:

message: This is a test