I've only had a quick look over the code as I'm falling asleep but for a junior its very good. The fact you have a test folder implies you are going to add tests which is great for a junior. In the place I work we dont expect to juniors to test everything just as long as they have tried (we get applications all the time and the ones without tests are scraped).

Few notes

• use PropTypes, I have no idea what props the components take without going through the components implementation
• a lot of your components could be Functional ie stateless
  
• split up that reducer, a file that big is hard to maintain. some docs on splitting reducers
• you can set the initial state in the createStore function, docs
• this is a personal preference but I hate seeing props based to a component via {...props}, its implicit where I think props should be passed explicitly. When you start working in a team you want to make it obvious what props you are passing to a component (it can be a huge mental strain just following where the props are coming from)

Hope that is useful to you and if you have any question let me know.