Convenience init for RippleView

[jstnheo]

Added a convenience initializer to RippleView for easier initialization and default value for tint color

let view = RippleView(image: UIImage(named: "q"), tintColor: UIColor(red: 0.3, green: 0.7, blue: 1, alpha: 1))

let view2 = RippleView(image: UIImage(named: "q"))

let view3 = RippleView()
view3.coreImage = UIImage(named: "q")
view3.tintColor = UIColor(red: 0.3, green: 0.7, blue: 1, alpha: 1)

view, view2, view3 all have the same result