Update project file to Swift 2.3

XCode/Swifter.xcodeproj/project.pbxproj

@@ -540,6 +540,7 @@
 				TargetAttributes = {
 					7AE893E61C05127900A29F63 = {
 						CreatedOnToolsVersion = 7.1;
+						LastSwiftMigration = 0800;
 					};
 					7AE893FA1C0512C400A29F63 = {
 						CreatedOnToolsVersion = 7.1;
@@ -858,6 +859,7 @@
 				PRODUCT_NAME = Swifter;
 				SDKROOT = iphoneos;
 				SKIP_INSTALL = YES;
+				SWIFT_VERSION = 2.3;
 				VERSIONING_SYSTEM = "apple-generic";
 				VERSION_INFO_PREFIX = "";
 			};
@@ -884,6 +886,7 @@
 				PRODUCT_NAME = Swifter;
 				SDKROOT = iphoneos;
 				SKIP_INSTALL = YES;
+				SWIFT_VERSION = 2.3;
 				VERSIONING_SYSTEM = "apple-generic";
 				VERSION_INFO_PREFIX = "";
 			};