Implement rotation animations.

This introduces a small new feature for ScaleAnimation allowing
the scaling factor to be expressed as a percentage of the object
(which is the same as the existing float interpretation), a
percentage of the container, or a fixed dimension.  Maybe not
useful for anything else, but I needed it for this.

Also fix a bug in how transformation matrices were propagated
from the Animation to Surface Flinger, so that rotate and skew
animations will actually work. :p

Change-Id: I301f4caa2147aa35564b5e511cb9c0b368d2425d