How to customize like fonts?

README says it is customizable but don't see an option. For example, action label font is hardcoded as "Avenir-Heavy". I can always do:

```
let okAction = PMAlertAction(title: "OK", style: .default, action: { () in
            print("Capture action OK")
        })
okAction.titleLabel?.font = ... my font ...
```

Are there other ways without looking into the code