Update README file for Xcode 8.3 and Swift 3.1

Author: jgonfer

README.md

@@ -1,8 +1,8 @@
 ### SFSafariViewController Tutorial for Swift 3
 [![BuddyBuild](https://dashboard.buddybuild.com/api/statusImage?appID=58d3d0155223860001760619&branch=master&build=latest)](https://dashboard.buddybuild.com/apps/58ad1da0b6bc0901002edae5/build/latest?branch=master)
 [![platform](https://img.shields.io/badge/platform-ios-lightgrey.svg?style=flat)](https://developer.apple.com/ios/)
-[![env](https://img.shields.io/badge/env-xcode_8.2.1-lightgrey.svg?style=flat)](https://developer.apple.com/xcode/)
-[![swift](https://img.shields.io/badge/swift-3.0.2-orange.svg?style=flat)](https://swift.org/)
+[![env](https://img.shields.io/badge/env-xcode_8.3-lightgrey.svg?style=flat)](https://developer.apple.com/xcode/)
+[![swift](https://img.shields.io/badge/swift-3.1-orange.svg?style=flat)](https://swift.org/)
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