Passing an image to initializer does nothing

[marchinram]

https://github.com/uber/UberSignature/blob/master/Sources/Swift/SignatureDrawingViewController.swift#L40

public init(image: UIImage? = nil) {
        super.init(nibName: nil, bundle: nil)
    }

The passed image is not used or shown in view controller when using this initializer, I would expect that when I pass an image to this initializer it would show the image

[arashetm]

As objective-c code change the init method to:

public init(image: UIImage? = nil) {
        super.init(nibName: nil, bundle: nil)
        presetImage = image
    }

[AntonioFerreira94]

When can you merge this fix to the master?