Let Widget class don't support cascaded opacity and cascaded color on default.
Update CCScene.cpp

in line 157, here need to create  and add camera, if not ,in the function createWithPhysics, will show black screen.
Merge pull request #7723 from jimmystar/patch-3

Update CCScene.cpp
[AUTO]: updating luabinding automatically
Merge pull request #7726 from CocosRobot/update_lua_bindings_1407720566

[AUTO]: updating luabinding automatically
[AUTO][ci skip]: updating cocos2dx_files.json
Merge pull request #7727 from CocosRobot/update_cocosfiles_1407720774

[AUTO][ci skip]: updating cocos2dx_files.json
Merge pull request #7683 from andyque/fixWidgetDefaultCascadColorAndOpacity

Let Widget class don't support cascaded opacity and cascaded color on default.