take care of the screen scale when drawing background. Fixes #1
take care of the screen scale when drawing background. Fixes #1

Fixed a bug that creates blurry backgrounds on retina screens.

AlexanderMazaletskiy/WMGaugeView,sakrist/WMGaugeView,shabbirh/WMGaugeView,ahmgsk/ios-GaugeView,Will-tm/WMGaugeView