adding mechanism to override the smartctl commands used by scrutiny for device scanning, device identification and smart data retrieval.

adding tests for command overrides.

rename GetScanOverrides() to GetDeviceOverrides()

fixes #255

collector/pkg/models/scan_override.go

@@ -4,4 +4,8 @@ type ScanOverride struct {
 	Device     string   `mapstructure:"device"`
 	DeviceType []string `mapstructure:"type"`
 	Ignore     bool     `mapstructure:"ignore"`
+	Commands   struct {
+		MetricsInfoArgs  string `mapstructure:"metrics_info_args"`
+		MetricsSmartArgs string `mapstructure:"metrics_smart_args"`
+	} `mapstructure:"commands"`
 }