use Configuration::getInstance()->supportsShareableVAO() in place of CC_TEXTURE_ATLAS_USE_VAO;
fix GL_EXT_discard_framebuffer always disable in EAGLView.mm;
fix GL_EXT_discard_framebuffer always disable in EAGLView.mm (fix compile fail on early iOS SDK 4.0);
Merge branch 'develop' of https://github.com/cocos2d/cocos2d-x into feature/configuration_VAO_runtime

Conflicts:
	cocos2dx/CCConfiguration.cpp
	cocos2dx/draw_nodes/CCDrawNode.cpp
	cocos2dx/particle_nodes/CCParticleSystemQuad.cpp
	cocos2dx/platform/android/CCEGLView.cpp
	cocos2dx/platform/ios/EAGLView.mm
	cocos2dx/textures/CCTextureAtlas.cpp
	cocos2dx/textures/CCTextureAtlas.h
remove conflicts files;
put '{' in a new line to follow cocos2d-x coding style
Merge pull request #4207 from bmanGH/feature/configuration_VAO_runtime

[ci skip]Configuration of VAO in runtime