CI: Update Xcode version to 8.3, move to Swift 3.1
CI: Update Xcode version to 8.3, move to Swift 3.1

3DprintFIT/octoprint-ios-client,3DprintFIT/octoprint-ios-client,3DprintFIT/octoprint-ios-client,3DprintFIT/octoprint-ios-client,3DprintFIT/octoprint-ios-client