Set AlarmActivity's animator progress directly

Bug: 17935860

Power save mode changes the ValueAnimator's internal duration scale,
which prevents ValueAnimator#setCurrentPlayTime(long) from functioning
correctly (b/17404930). As a workaround, set the animator's animated
fraction directly, jumping the animation to a specific point that isn't
dependent on the animator's duration scale or the current play time.
This functionality isn't yet exposed (b/17938711), so the internal
ValueAnimator#animateValue(float) method must be invoked via reflection.

Change-Id: I1af77300b3a95e62c960d482fb2f0263cbbc4fc6