KEYCODE_BACK: escape->backspace
Merge branch 'v3_assets_manager' of https://github.com/joshuastray/cocos2d-x into v3_assets_manager
add new assets manager files in CMakeLists.txt
Revert "KEYCODE_BACK: escape->backspace"

This reverts commit f00563399219651aa848ac21284f8c52c6191338.
Merge pull request #49 from joshuastray/v3_assets_manager

add new assets manager files in CMakeLists.txt
Merge branch 'v3_assets_manager' of git://github.com/cocos2d-html5/cocos2d-x into v3_assets_manager