Updated react and router - #4

@moshie I appreciate the pull request.

Do you mind cherry-picking the changes over to the branch upgrade-react-router-4, which has the latest code from master? This will ensure consistency between my tutorials.

Also, do you mind not bumping react and react-dom and not committing yarn.lock or package-lock.json? I'm thinking about doing those tasks separately in one of my later tutorials. Thanks!

@remarkablemark No Problem, been enjoying the tutorials!

Yeah sure thing, I'll make those changes on the upgrade-react-router-4 hopefully some time later if not tommorow 👍

@moshie Thanks for taking the time to do this.

When I do get to making the video, what's the best way that I can give you credit for your contribution? Would a link to your GitHub work?

Hope this is all ok!

A link to my github would be cool thanks 👍