title: MFMailComposeViewController is not working under iOS 7
body: <p><code>[MFMailComposeViewController canSendMail]</code> works well under iOS 6 application, but fail for under iOS7.</p>
  
  <p>iOS 6 mail function:</p>
  
  <pre><code>if ([MFMailComposeViewController canSendMail])
  {
      MFMailComposeViewController *mailer = [[MFMailComposeViewController alloc] init];
      mailer.mailComposeDelegate = self;
      [mailer setSubject:@"A Message from Bloomingkids"];
      NSArray *toRecipients = [NSArray arrayWithObjects:@"support@bloomingkids.com", nil];
      [mailer setToRecipients:toRecipients];
      UIImage *myImage = [UIImage imageNamed:@"bloomingKidsLogo.png"];
      NSData *imageData = UIImagePNGRepresentation(myImage);
      [mailer addAttachmentData:imageData mimeType:@"image/png" fileName:@"Images"];
      NSString *emailBody = @"Have you seen the Bloomingkids web site?";
      [mailer setMessageBody:emailBody isHTML:NO];
      [self presentViewController:mailer animated:YES completion:nil];
  }
  else
  {
      UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Failure"
                                                      message:@"Your device doesn't support the composer sheet"
                                                     delegate:nil
                                            cancelButtonTitle:@"OK"
                                            otherButtonTitles: nil];
      [alert show];
  }
  </code></pre>
  
  <p>Note: It's working on simulator but not on iPad. The error was <strong>Your device doesn't support composer sheet</strong></p>