Bring cancel disk task back

Kingfisher/Info.plist

@@ -19,7 +19,7 @@
 	<key>CFBundleSignature</key>
 	<string>????</string>
 	<key>CFBundleVersion</key>
-	<string>267</string>
+	<string>282</string>
 	<key>NSPrincipalClass</key>
 	<string></string>
 </dict>

Kingfisher/KingfisherManager.swift

@@ -45,11 +45,11 @@ public class RetrieveImageTask {
     */
     public func cancel() {
         // From Xcode 7 beta 6, the `dispatch_block_cancel` will crash at runtime.
-        // So we removed disk retrieve canceling now.
+        // It fixed in Xcode 7.1.
         // See https://github.com/onevcat/Kingfisher/issues/99 for more.
-//        if let diskRetrieveTask = diskRetrieveTask {
-//            dispatch_block_cancel(diskRetrieveTask)
-//        }
+        if let diskRetrieveTask = diskRetrieveTask {
+            dispatch_block_cancel(diskRetrieveTask)
+        }
         
         if let downloadTask = downloadTask {
             downloadTask.cancel()

KingfisherTests/ImageCacheTests.swift

@@ -211,7 +211,8 @@ class ImageCacheTests: XCTestCase {
         format = testImagePNGData.kf_imageFormat
         XCTAssertEqual(format, ImageFormat.PNG)
         
-        format = NSData(bytes: [1,2,3,4,5,6,7,8], length: 8) .kf_imageFormat
+        let raw = [1,2,3,4,5,6,7,8]
+        format = NSData(bytes: raw, length: 8) .kf_imageFormat
         XCTAssertEqual(format, ImageFormat.Unknown)
     }