Add skeletontest and various fixes

- Add SkeletonTest for easy debugging, see http://youtu.be/8E0gtpBTfA0
- Default texture uv wrap to GL_REPEAT
- Add mtl shininess and opacity
- Fix BlendingAttribute constructor
- Fix MeshBuilder#box when not using normal
- GLES10: Default cullface to GL_BACK
- GLES10: Use GL_QUADRATIC_ATTENUATION for intensity, just like defaultshader
- GLES10: Use glLightModelfv for ambient
- GLES10: Use glMaterialfv when lighting is applied