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!
Idk this one might actually be a bit of a pain to load? But I'd want to optimize it differently anyway, and there's overhauls we're already planning to do here.
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.
