Update SwiftTask to v2.2.1 & fix 2a65b9b where xcodebuild sometimes failed by removing Carthage.build folder in xcodeproj.
Merge pull request #5 from ReactKit/carthage

Update SwiftTask to v2.2.1 & fix 2a65b9b where xcodebuild sometimes failed by removing Carthage.build folder in xcodeproj.