Default camera width to 320x240 and default to joystick

Most webcams allow for a resolution to be set at 320x240, so it
makes sense for the defaults to be bumped slightly to meet this.
In the future, this should be configurable, similar to how it is
done in the Cheese photo capture application.

The default controller has also been changed to the joystick.  While
the other controller works as expected, the boundaries of the image
are set to the boundaries for the image, requiring the user's face
to fill the entire webcam.  The joystick controller does not
require this, as it works relative to the original calibrated point.
Tweak the joystick a little

When the camera loses the location of the nose, it previously
stopped moving the cursor.  Considering this is a joystick, and we
calculate the direction of the cursor constantly, we can assume the
user is still planning on moving in the last calculated direction.

This also moves the cursor relative to its position on the screen
instead of relative to the last calculated location.  This allows
the cursor to be manually moved if needed, and it will still work
as expected without jumping the cursor to the last location.