Fix issue where widget was incorrectly 4x2 on some devices

The correct equation to use is: 70 x n - 30
For some reason, applying that equation to the widget as well
resulted in a 3x1 widget on some devices.

See also:
http://developer.android.com/guide/practices/ui_guidelines/widget_design.html#anatomy_determining_size

Signed-off-by: Greg Meiste <greg.meiste@gmail.com>
Include a widget preview for Android 3.0+ devices. For #17

Signed-off-by: Greg Meiste <greg.meiste@gmail.com>