CCImage.cpp: initWithS3TCData() - When there is s3tc hardware support, set PixelFormat before loading mipmaps, to allow for textures with no mipmaps.
Merge branch 's3tc_nomipmaps' of github.com:wefiends/cocos2d-x into s3tc_nomipmaps
CCImage.cpp: If dds header reports 0 mipmaps, force _numberOfMipmaps to 1 to enable software decoding. Set _renderFormat just once for both hardware and software decoding (moved out of "load mipmaps" loop).