title: didSelectRowAtIndexPath not being called with TTTableViewController
body: <p><strong>The challenge:</strong>
  I'd like to do some action if the user touches a TableItem. </p>
  
  <p><strong>The problem:</strong> The didSelectRowAtIndexPath method is never called? Did I miss something?</p>
  
  <hr>
  
  <p><em>PortfolioViewController.h</em></p>
  
  <pre><code>@interface PortfolioViewController : TTTableViewController &lt;TTTableViewDelegate&gt; 
  {
  
  }
  
  @end
  </code></pre>
  
  <p><em>PortfolioViewController.m</em></p>
  
  <pre><code>@implementation PortfolioViewController
  
  - (id)init {
   if (self = [super init]) {
    self.title = @"Portfolio";
    self.tableViewStyle = UITableViewStylePlain;
    self.tableView.autoresizingMask = UIViewAutoresizingFlexibleWidth| UIViewAutoresizingFlexibleHeight;
    self.variableHeightRows = YES;  
  
    PortfolioDataSource *ds = [[[PortfolioDataSource alloc] init] autorelease];
    CasesModel *cm = [[[CasesModel alloc] init] autorelease];
    ds.model = cm; 
  
    self.dataSource = ds;
   }
   return self;
  }
  
  #pragma mark -
  #pragma mark Table Delegate Methods
  - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath 
  {
   NSLog(@"touched");
  }
  
  @end
  </code></pre>