- can't reliably use sinon.spy to tell whether a thing has been called,
so we listen for events instead and check server.requests()
- make sure to request the next page before dispatching `loadedImages` so
we can `server.respond()` to the request in the event handler if we want to
- also moves `localeDateString` in the openstreetcam service from parsing
code to display code, because it's very slow (we can just do this for the
images we look at, instead of all images we fetch)
e981cd5dd5