add simple webhook feature for peer, interface and user events (#398)

internal/config/config.go

@@ -62,6 +62,8 @@ type Config struct {
 	Database DatabaseConfig `yaml:"database"`
 
 	Web WebConfig `yaml:"web"`
+
+	Webhook WebhookConfig `yaml:"webhook"`
 }
 
 // LogStartupValues logs the startup values of the configuration in debug level
@@ -158,6 +160,10 @@ func defaultConfig() *Config {
 		LinkOnly:       false,
 	}
 
+	cfg.Webhook.Url = "" // no webhook by default
+	cfg.Webhook.Authentication = ""
+	cfg.Webhook.Timeout = 10 * time.Second
+
 	return cfg
 }