title: how to set text of titleForHeaderInSection to AlignmentCenter
body: <p>i  used  the  follow  code to set the title at the group tableview title header,but default the text is AlignmentLeft,how to AlignmentCenter?</p>
  
  <pre><code>- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section {
      if(section==0){
          return NSLocalizedString(@"more_titlehead_one", nil);
      }else if (section==1){
          return NSLocalizedString(@"more_titlehead_two", nil);
      }else{
          return NSLocalizedString(@"more_titlehead_three", nil);
      }
  
  
  }
  </code></pre>