Tableview fixes

Two small UITableView-related fixes to the samples:

Beers sample: Fix cell selection bug
    
* Previously, in the "Beers" sample, if the user clicked on a row of the
    list of beers, that row wuold remain highlighted in blue.

Fonts app: improved selection UI
    
* As with most iPhone apps, now when you click the "Back" button to
    return to the full list of fonts, the previously-selected font
    momentarily blinks blue (selected), and then quickly fades out.