Once again, SwitchEasy has put its own unique spin on an established accessory category—this time, it’s entering the MacBook shell market with Cocoon ($50) for the 15” MacBook Pro with Retina display. Although we’re a bit surprised the price isn’t somewhat lower—SwitchEasy is usually known for ultra-affordable accessories—Cocoon sells for roughly the same price as competing alternatives. The hard polycarbonate…