add support for custom Java Drawables

This is made possible, by adding a second Canvas implementation which
can be used to render directly to GdkSnapshot objects

For now the only implemented method is drawBitmap(), this is already
enough to make VectorDrawableCompat functional

src/api-impl/android/graphics/drawable/ShapeDrawable.java

@@ -1,6 +1,5 @@
 package android.graphics.drawable;
 
-import android.graphics.Canvas;
 import android.graphics.Paint;
 import android.graphics.drawable.shapes.Shape;
 
@@ -9,11 +8,5 @@ public class ShapeDrawable extends Drawable {
 	public ShapeDrawable(Shape shape) {}
 
 	public Paint getPaint() {return new Paint();}
-
-	@Override
-	public void draw(Canvas canvas) {
-		// TODO Auto-generated method stub
-		throw new UnsupportedOperationException("Unimplemented method 'draw'");
-	}
 	
 }