SimplePingHelper with ARC and call by block

[shiweifu]

you can use SimplePingHelper like:

  [SimplePingHelper ping:@"www.apple.com"
                callback:^(NSNumber *b){
              if(b.boolValue)
              {
                NSLog(@"%@", @"success");
                [self log:@"success"];

              }
              else
              {
                NSLog(@"%@", @"failure");
                [self log:@"failure"];
              }
  }];

I also add ARC support