Fix import compatibility for OSX target

CryptoSwift/CryptoSwift.h

@@ -6,7 +6,7 @@
 //  Copyright (c) 2014 Marcin Krzyzanowski. All rights reserved.
 //
 
-#import <UIKit/UIKit.h>
+#import <Foundation/Foundation.h>
 
 //! Project version number for CryptoSwift.
 FOUNDATION_EXPORT double CryptoSwiftVersionNumber;

CryptoSwiftTests/CipherTests.swift

@@ -6,7 +6,7 @@
 //  Copyright (c) 2014 Marcin Krzyzanowski. All rights reserved.
 //
 
-import UIKit
+import Foundation
 import XCTest
 import CryptoSwift
 

CryptoSwiftTests/ExtensionsTest.swift

@@ -6,7 +6,7 @@
 //  Copyright (c) 2014 Marcin Krzyzanowski. All rights reserved.
 //
 
-import UIKit
+import Foundation
 import XCTest
 import CryptoSwift