Animate starting windows when keyguard dismissed.

Starting windows are displayed prior to their app windows visibility
being set. Consequently the WindowToken.hidden boolean for starting
windows is still true even when it is shown. The keyguard logic uses
the method WindowState.isVisibleNow to determine whether to animate
each window. This method incorrectly determined that starting windows
were not visible based on WindowToken.hidden and consequently didn't
animate in the starting window.

This change fixes isVisibleNow() to correctly determine when
starting windows are visible and animates them in as part of the
keyguard transition.

This change also adds keyguard debug.

Partially fixes bug 15991916.

Change-Id: Iac3e5f3f33876be5801ec619bbe7a1579e648322