Upgrade to React Router v4

[tech4him1]

- Summary

Close #413.

Upgrade React Router (and react-router-redux) to version 4.

- Test plan

Manually test routing (unless someone else has a better testing method).

- Description for the changelog

Upgrade to React Router v4.

- A picture of a cute animal (not mandatory but encouraged)

[tech4him1]

The current problem I am having is that the location is passed as a context prop, not a true prop. So, for example, if you go from one collection to another, the URL will update, but the list of entries will not, as it still gets the original :name param.

Here is a document on the fixes: https://github.com/ReactTraining/react-router/blob/master/packages/react-router/docs/guides/blocked-updates.md. @erquhart @Benaiah do either of you have any suggestions? I'm thinking the more performant approach would be better, just wrapping each component in a simple arrow function instead of trying to use withRouter everywhere.

[erquhart]

@tech4him1 is your last comment still an issue? That would make this WIP, just checking status.

[tech4him1]

@erquhart For status, it seems to be working for me, so it is ready for review (not WIP). I would appreciate you reading that article, though, to make sure you agree with how I implemented the fix (d3366ab) and make sure no more fixes need to be done.

[tech4him1]

One thing I'm not quite sure about is whether this is the best way to pass newRecord through here.

[tech4him1]

I think the most "proper" way to do this would be to move the actual logic for newRecord to EntryPage itself. @erquhart @Benaiah do you mind that?

[erquhart]

You could clean it up a little: render={props => <EntryPage {...props} newRecord />}

I think the boolean prop will work that way, right?

[tech4him1]

@erquhart @Benaiah I've just been reading through this: https://css-tricks.com/react-router-4/#article-header-id-4.
I'm wondering if this would be a better way to structure our routes -- it seems a lot cleaner.

[Benaiah]

@tech4him1 based on our conversation in Gitter (pasted below for future reference), I think that's fine in some situations, but only where there's a clear advantage to doing so. Either way, I'd like to review and merge this as is as we discussed in Gitter.

Benaiah Mischenko @Benaiah 12:17
from what I'm seeing that's more for pages that are really nested. It could clean up auth, but most of the other routes have totally separate pages for each different route match
you don't have the issue he has in the article of additions to URLs drilling further into a single page (like if CollectionPage and EntryPage were the same component)
maybe I'm missing something but that seems to be the primary advantage of what he's suggesting here

Caleb @tech4him1 12:18
I agree on that part of it.

Benaiah Mischenko @Benaiah 12:18
I'm kind of a fan of the flat routing too, it makes it easy to know that you haven't missed any routes somewhere when debugging that stuff
auth might be a good spot for that technique. I don't see anything that indicates you can't do both depending on what's more appropriate for the situation
but CollectionPage and EntryPage have no shared UI pieces that I'm aware of

Caleb @tech4him1 12:20
what about for newRecord with EntryPage

Benaiah Mischenko @Benaiah 12:21
ah, that might be a good one. though OTOH it means EntryPage is now concerned with routing where it wasn't before. I don't think that's too much of an issue with the top-level page components, but I don't want routing concerns to couple themselves more than one or two layers into the UI
so I think that may also be a good fit, but I wouldn't want to blindly use that approach for everything, since I'd like most of the UI to remain decoupled. does that make sense?
the rule of thumb I'm thinking of is that coupling the component to the router is probably ok if the name of the component ends with Page 😛

[Benaiah]

LGTM - code seems fine and manually testing the routing didn't bring up any regressions. 404s aren't working when they're a valid route for a nonexistent resource, but that's not a regression.