Bump to version 4.0 in ancillary files

Author: matthewpalmer

README.md

@@ -30,7 +30,7 @@ How is Locksmith different to other keychain wrappers?
 [![Carthage compatible](https://img.shields.io/badge/Carthage-compatible-4BC51D.svg?style=flat)](https://github.com/Carthage/Carthage)
 [![Build Status](https://travis-ci.org/matthewpalmer/Locksmith.svg?branch=master)](https://travis-ci.org/matthewpalmer/Locksmith)
 
-* Locksmith 3.0 and greater is Swift 3 compatible. See the `swift-2.3` branch for compatibility with older versions of Swift.
+* Locksmith 4.0 and greater is Swift 4 compatible. See the `swift-3.1` branch for compatibility with older versions of Swift.
 
 ### CocoaPods
 

Source/Info.plist

@@ -15,7 +15,7 @@
 	<key>CFBundlePackageType</key>
 	<string>FMWK</string>
 	<key>CFBundleShortVersionString</key>
-	<string>3.0</string>
+	<string>4.0</string>
 	<key>CFBundleSignature</key>
 	<string>????</string>
 	<key>CFBundleVersion</key>