Upgrade dependency to include React 15.0.0

[jwngr]

Change log for React 15.0.0 here.

I'll gladly take a PR from the community on this one if anyone sees this. We need to add 15.x.x here and here as well as upgrade all dev dependencies here to 15.x.x. We also should update the React dependency numbers in the README.md here. If all tests pass and the examples all still work, we should be good to ship it.

[ThariqS]

--> #89

[jwngr]

Just to close the loop here, this was shipped in version 0.7.0 a few weeks ago.