Upgrade React

Summary:
to version 8db2ba9130d8e1034ad60fb3cf429ecf02ce1df9 plus these changes: https://gist.github.com/spicyj/9f2c461d818cfdbede96.

- remove all references to autoBind (it's automatic!)
- now <input value={...}> actually mandates that the value is that, so adapt the places where that changes things
- setState is now async thanks to my pull request, so add a callback to onChange in order to call focus() at the right times
- add keys to things to get rid of some warnings

Reviewers: emily, jakesandlund, alex

Reviewed By: alex

CC: joel

Differential Revision: http://phabricator.khanacademy.org/D2947