Update to Xcode 8 + Swift 2.3

Author: Jose Alcalá Correa

Example/Example.xcodeproj/project.pbxproj

@@ -370,6 +370,7 @@
 				TargetAttributes = {
 					6003F589195388D20070C39A = {
 						DevelopmentTeam = 8LA8LT5B49;
+						LastSwiftMigration = 0800;
 					};
 				};
 			};
@@ -563,6 +564,7 @@
 				PROVISIONING_PROFILE = "";
 				SWIFT_OBJC_BRIDGING_HEADER = "GSKStretchyHeaderView/Example-Bridging-Header.h";
 				SWIFT_OPTIMIZATION_LEVEL = "-Onone";
+				SWIFT_VERSION = 2.3;
 				WRAPPER_EXTENSION = app;
 			};
 			name = Debug;

GSKStretchyHeaderView/GSKStretchyHeaderView.xcodeproj/project.pbxproj

@@ -225,10 +225,12 @@
 					82BEE61F1D3AAA4300A3C3AA = {
 						CreatedOnToolsVersion = 7.3.1;
 						DevelopmentTeam = 8LA8LT5B49;
+						LastSwiftMigration = 0800;
 					};
 					82BEE6291D3AAA4300A3C3AA = {
 						CreatedOnToolsVersion = 7.3.1;
 						DevelopmentTeam = 8LA8LT5B49;
+						LastSwiftMigration = 0800;
 					};
 				};
 			};
@@ -406,6 +408,7 @@
 				PRODUCT_BUNDLE_IDENTIFIER = org.gskbyte.GSKStretchyHeaderView;
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SKIP_INSTALL = YES;
+				SWIFT_VERSION = 2.3;
 			};
 			name = Debug;
 		};
@@ -422,6 +425,7 @@
 				PRODUCT_BUNDLE_IDENTIFIER = org.gskbyte.GSKStretchyHeaderView;
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SKIP_INSTALL = YES;
+				SWIFT_VERSION = 2.3;
 			};
 			name = Release;
 		};
@@ -432,6 +436,7 @@
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks @loader_path/Frameworks";
 				PRODUCT_BUNDLE_IDENTIFIER = org.gskbyte.GSKStretchyHeaderViewTests;
 				PRODUCT_NAME = "$(TARGET_NAME)";
+				SWIFT_VERSION = 2.3;
 			};
 			name = Debug;
 		};
@@ -442,6 +447,7 @@
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks @loader_path/Frameworks";
 				PRODUCT_BUNDLE_IDENTIFIER = org.gskbyte.GSKStretchyHeaderViewTests;
 				PRODUCT_NAME = "$(TARGET_NAME)";
+				SWIFT_VERSION = 2.3;
 			};
 			name = Release;
 		};