Make placeholderTextColor settable

[jordanhbuiltbyhq]

I'd like to change the placeholderTextColor but it's a constant not an inspectable variable like titleTextColour. This is what I desire. :)

    @IBInspectable var placeholderTextColor:UIColor = UIColor.lightGray.withAlphaComponent(0.65) {
        didSet {
            if !isFirstResponder {
                hintLabel.textColor = placeholderTextColor
            }
        }
    }