Add React events to externs/react.js

http://facebook.github.io/react/docs/events.html
Release v5.2.16
Release v5.2.17
Release v5.2.18
Improve docs for este.react.unmount.
Fix Closure Library version til new Compiler will be released.
Release v5.2.19
Damn Crockford, JSON should allow comments.
Release v5.2.20
Update React externs. Close #20
Release v5.2.21
Add boolean as child into React externs.

http://facebook.github.io/react/tips/false-in-jsx.html
Release v5.2.22
este.labs.Route url method does not require optional params to be defined as undefined anymore.
Release v5.2.23
Update package.json dev dependencies.
Release v5.2.24
Release v5.2.25
Increase test timeouts for slower computers.
Release v5.2.26