Update to React 0.11 and fix child context types.

Unfortunately had to punt on PropTypes as I [couldn't find](https://groups.google.com/d/msg/reactjs/4i68_ly4iRM/zlbtMh4jgdgJ) any better option than `React.PropTypes.all`, but it works and it gets to ~0.11.

I don't see any documentation for the entity encoding change in 0.11 but perhaps I missed it. In any case that change was also required to pass tests.

This is a fix for #66 and supersedes #73.