remove unused codes in CCTexture2D
Use the image format instead of RGBA8888 when initializing a texture, this would remove the redudant conversion and save memories.
Merge pull request #6982 from CocosRobot/update_lua_bindings_1401951865

[AUTO]: updating luabinding automatically
add new tests for different pixel formats
remove the new images and use the old ones.
Merge pull request #6979 from visiblelight/TextureOptimize

Texture Optimize