Some important little upgrades but mostly straightforward!
Note that there's still a known issue where item searches crash, I was hoping that this was a bug in Rails 4.2 that would be fixed on upgading to 5, but nope, oh well!
Also uhh I just got a bit silly and didn't actually mean to go all the way to 5.2 in one go, I had meant to start at 5.0… but tbh the 5.1 and 5.2 changes seem small, and this seems to be working, so. Yeah ok let's roll!
Back in the day, `all` would immediately load up a query into an array, but now I think it's an alias for what `scoped` used to be: a relation that contains everything.
Ohh ok, without this change all of our `scope`s were just immediately evaluating the argument and fetching _all_ such matching records immediately, instead of waiting to actually be called. This led to bugs like `pet_type.as_json` returning ALL pet states in the whole db, because the `PetState.emotion_order` scope was being treated as a single predefined query, rather than a query fragment to merge into the current context.
This also explains what happened in 724ed83: that's why things before the scope in the query were being ignored.
