fix runner to use global instance

api/models/app.go

@@ -17,7 +17,6 @@ var (
 	ErrAppsNothingToUpdate = errors.New("Nothing to update")
 	ErrAppsMissingNew      = errors.New("Missing new application")
 	ErrUsableImage         = errors.New("Image not found")
-	ErrNewRunnerDriver     = errors.New("Error creating the runner driver")
 )
 
 type App struct {