Fix ImageView.setImageResource() to no-op if the id passed in is 0.
Add ability to get the callbacks added to the SurfaceHolder returned by ShadowSurfaceView.getHolder().
If resource ID is 0, call set image drawable to null.
Merge pull request #691 from erichaugh/master

Fix ImageView.setImageResource() to no-op if the id passed in is 0.