Add fix for pixelation and bluriness on retina

Update podspec

Author: Luis Padron

UICircularProgressRing.podspec

@@ -2,7 +2,7 @@
 Pod::Spec.new do |s|
 
   s.name         = "UICircularProgressRing"
-  s.version      = "1.1.1"
+  s.version      = "1.1.2"
   s.summary      = "A highly customizable circular progress bar for iOS written in Swift 3"
 
   s.description  = <<-DESC

UICircularProgressRing/UICircularProgressRingView.swift

@@ -533,6 +533,10 @@ import UIKit
 
      */
     private func initialize() {
+        // Helps with pixelation and blurriness on retina devices
+        self.layer.contentsScale = UIScreen.main.scale
+        self.layer.shouldRasterize = true
+        self.layer.rasterizationScale = UIScreen.main.scale * 2
         self.ringLayer.value = value
         self.ringLayer.maxValue = maxValue
         self.ringLayer.viewStyle = viewStyle