Use peerDependencies

[eldh]

Use peerDependencies to avoid react being loaded twice (as adviced here: clayallsopp/react.backbone#26 (comment)). Fucked up the commit history a bit but it should be fine I think...

[kalasjocke]

@eldh Interesting, makes sense to use peerDependencies to specify the React version since this is fact a plugin. However, the build fails on Travis, do you have any clever ideas on how to make this work? Also, could you just rebase and squash all your commits into one and force push that one to this branch? We would get a lot cleaner history then.

[eldh]

I think the way react-router does it makes sense, although it's a bit weird to define the dependency twice: https://github.com/rackt/react-router/blob/master/package.json. Peer dependency for production and dev dependency for running tests.

[kalasjocke]

I think so to! Thanks for this pull request @eldh! 🍰