Removed peer dependancy because of error

Removed the peerDependancy because when we install with yarn, the following error occurs:

warning " > [email protected]" has incorrect peer dependency "react@^15.4.1".

Thank you very much for opening this PR, @tgrrr.

I assume yarn is showing you a warning because you are using a different version of React. I'm OK with bumping the React version (if this package still works), but I wouldn't remove the peer dependency.

I hope this makes sense.

@MicheleBertoli thanks.

Since I've done this PR, I've come across a few accounts of yarn peer dependency bugs, so it might also be that. Eg. https://github.com/yarnpkg/yarn/issues/4433