修改背景图片，调整坐标
#	modified:   Classes/GravityBallConfig.h
#	modified:   Classes/HelloWorldScene.cpp
#	new file:   Resources/bg.png
#	new file:   Resources/block.png
#	new file:   Resources/circle.png
#	new file:   proj.android/assets/bg.png
#	new file:   proj.android/assets/block.png
#	new file:   proj.android/assets/circle.png
#	modified:   proj.android/libs/armeabi/libgame.so
#	modified:   proj.win32/main.cpp