Update .swift-version to 4.1 (#20)

Author: Ian Partridge

.swift-version

@@ -1 +1 @@
-4.0.3
+4.1

.travis.yml

@@ -1,4 +1,4 @@
-# Travis CI build file for KituraBuddy.
+# Travis CI build file for KituraContracts.
 
 # whitelist (branches that should be built)
 branches:
@@ -12,18 +12,17 @@ matrix:
     - os: linux
       dist: trusty
       sudo: required
-    - os: osx
-      osx_image: xcode9.2
-      sudo: required
       env: SWIFT_SNAPSHOT=4.0.3
     - os: linux
       dist: trusty
       sudo: required
-      env: SWIFT_SNAPSHOT=swift-4.1-DEVELOPMENT-SNAPSHOT-2018-02-06-a
     - os: osx
       osx_image: xcode9.2
       sudo: required
-      env: SWIFT_SNAPSHOT=swift-4.1-DEVELOPMENT-SNAPSHOT-2018-02-06-a
+      env: SWIFT_SNAPSHOT=4.0.3
+    - os: osx
+      osx_image: xcode9.3
+      sudo: required
 
 before_install:
   - git clone https://github.com/IBM-Swift/Package-Builder.git

README.md

@@ -27,7 +27,7 @@
 KituraContracts is a library containing type definitions shared by client (e.g. [KituraKit](https://ibm-swift.github.io/KituraKit/)) and server (e.g. [Kitura](https://ibm-swift.github.io/Kitura)) code. These shared type definitions include [Codable Closure Aliases](https://ibm-swift.github.io/KituraContracts/Typealiases.html), [RequestError](https://ibm-swift.github.io/KituraContracts/Structs/RequestError.html), [QueryEncoder](https://ibm-swift.github.io/KituraContracts/Classes/QueryEncoder.html), [QueryDecoder](https://ibm-swift.github.io/KituraContracts/Classes/QueryDecoder.html), [Coder](https://ibm-swift.github.io/KituraContracts/Classes/Coder.html), [Identifier Protocol](https://ibm-swift.github.io/KituraContracts/Protocols/Identifier.html#/s:15KituraContracts10IdentifierP5valueSSv) and [Extensions](https://ibm-swift.github.io/KituraContracts/Extensions.html#/s:SS) to String and Int, which add conformity to the Identifier protocol.
 
 ## Swift version
-The 0.0.x releases were tested on macOS and Linux using the Swift 4.0.3 binary. Please note that this is the default version of Swift that is include in [Xcode 9.2](https://developer.apple.com/xcode/).
+The 0.0.x releases were tested on macOS and Linux using the Swift 4.0.3 and 4.1 binaries. Please note that this is the default version of Swift that is include in [Xcode 9.2 and 9.3](https://developer.apple.com/xcode/).
 
 ## Community