Use a clear fill color for the circle. (#355)

* Use a clear fill color for the circle.

* Oops! Forgot to set the clear color for init?(coder:) as well

Author: Bharat Mediratta

LoopUI/Views/LoopStateView.swift

@@ -55,7 +55,7 @@ public final class LoopStateView: UIView {
         super.init(frame: frame)
 
         shapeLayer.lineWidth = 8
-        shapeLayer.fillColor = nil
+        shapeLayer.fillColor = UIColor.clear.cgColor
         shapeLayer.strokeColor = freshness.color.cgColor
 
         shapeLayer.path = drawPath()
@@ -65,7 +65,7 @@ public final class LoopStateView: UIView {
         super.init(coder: aDecoder)
 
         shapeLayer.lineWidth = 8
-        shapeLayer.fillColor = nil
+        shapeLayer.fillColor = UIColor.clear.cgColor
         shapeLayer.strokeColor = freshness.color.cgColor
 
         shapeLayer.path = drawPath()