[core] Normalize the API

[oliviertassinari]

• Reduce degree of freedom of the API with the color property. That's a tradeoff between correctness and verbosity.
  People should be able to recover from that breaking change quite easily as react is going to throw warnings.
• Transform all the classes to be camelCase (consistency)
• Use @owencm trick with double RAF to fix an animation issue with Chrome v59
• Fix animation with the older browsers like iOS 8.
• Add new tests to the Chip, withWidth, Textarea, ListItem +0.58%

[mbrookes]

I'm on board with the changes in principal, and gave it a quick scan. Too many changed files to review it thoroughly! 😆