Update sample project for Xcode 9 and Swift 4.0

[huebnerob]

Summary

This branch updates the StyledText sample project to enable successful building, running, and testing with Xcode 9 and Swift 4.0

Implementation Details

• Updated to newest versions of Nimble, Quick, and Nimble-Snaphots
• Set Swift version to 4.0 in build settings (no code changes were necessary 🎉)