Hey, I'm gonna be honest, there's ALOT of code here to do something really simple?
Just a quick summary:
Stylistic changes:

• In the index.html where you lower the head element (why?)
• DATA = {{WINDOW_DATA}} // this I like, because I think its the only way it can be done, though I would prefer something else, I've heard http2 push might also work??? Dunno, but I approve of this
• I like const {Thing} = this.props // Perhaps I'm not consistent everywhere, but I try, so looks like you tried to impose the const { Thing } = this.props // where you add the extra space
• I use leading commas, you don't
• I use no semi colons, you don't // I'm not saying they're wrong, just its super weird cause you can see the seams where different opinions meet

Code:

• You define a routes, why? React router v4 doesn't require routes defined, PLUS you redefine them in multiple places, which makes maintenance a bit of a pain
• You add superagent and a new ApiClient file (I already have an api file right?) plus, you don't explain why you need superagent? fetch is great and you don't need any extra dependencies, it doesn't add anything to the demo
• You don't redux right. Types go in the types, so that they're shared, rather than redefined
• You add a middleware file just to handle all the code loading?

Okay, this is taking me too much time, you've made a lot of changes that I feel could simply be done with:

action.set({start: true})
fetch(url)
  .then(v=>action.set({page: v}))
  .catch(error=>action.set({error})

Can you justify your changes?

Would love to have this feature well integrated 😍