dillon1000/react

Update to jest 15

Jest 15 has just been released and is way more awesome: http://facebook.github.io/jest/blog/2016/09/01/jest-15.html

This pull request updates jest from version 12 to 15. Right now there's a fix in jest around Symbol that hasn't been released yet, so this will break CI and cannot be merged it. But once it ships by the end of the day, we'll be good to go :)

See comments inline for all the changes I've done.