NetStats: Don't update stats when screen is off

Also moved registering of broadcast receiver and settings
observer to onAttachedToWindow() and unregistering to
onDetachedFromWindow() to avoid these being leaked.
New battery style - Icon with big text (1/2)

Samsung battery style

Change-Id: Ia58e9bf79099974bdbd260ea255cf979b632d790
Signed-off-by: kecinzer <kecinzer@gmail.com>