[ColorBitmapFont] add support for OSX Apple Color Emoji

this pull request, will need this skia patch https://github.com/jtg-gg/skia-src/commit/730410cee43e701070264f781340cc35c113d9b8

currently I'm working on windows version

![screen shot 2014-08-19 at 4 01 19 pm](https://cloud.githubusercontent.com/assets/4043527/3963193/ab7eff2e-2777-11e4-82af-c2e50e925d21.png)