Avoiding horizontal keypad navigation trapping within gallery.

Non touchscreen devices such as Google TV require the keypad
navigation to properly move the focus among widgets.

The Gallery is misshandling the keypress event and avoiding
the focus from going to other widgets on it's sides upon
keypress even after the user has reached it's first and
last items.

Change-Id: If32ee57e8513cac692deb161e1941d6cc85e3188
Signed-off-by: David Sobreira Marques <dpsmarques@gmail.com>