Remove trailing semicolons between method parameters and body (#1973)

Having a semi-colon between a method parameters list and a method
body is not not correct and is usually caused by a copy and paste
error while creating the method definition from its declaration.

Fixes the following compilation warnings when building with
-Wsemicolon-before-method-body (which is part of -Wextra):

  ASPINRemoteImageDownloader.mm:230:85: error: semicolon before method body is ignored [-Werror,-Wsemicolon-before-method-body]
  - (id <ASImageContainerProtocol>)synchronouslyFetchedCachedImageWithURL:(NSURL *)URL;
                                                                                      ^
  ASPINRemoteImageDownloader.mm:275:76: error: semicolon before method body is ignored [-Werror,-Wsemicolon-before-method-body]
                           completion:(ASImageDownloaderCompletion)completion;
                                                                             ^
  2 errors generated.

Fixes applied to both code, examples and samples in documentation.

examples_extra/CollectionViewWithViewControllerCells/Sample/ImageViewController.m

@@ -35,7 +35,7 @@
   self.imageView.contentMode = UIViewContentModeScaleAspectFill;
 }
 
-- (void)tapped;
+- (void)tapped
 {
   NSLog(@"tapped!");
 }