Have "duration" update using moment.js rather than relying on a cache refresh.

[sorry-app]

Have "duration" update using moment.js rather than relying on a cache refresh.

[SirRawlins]

I think in order to do this, we'll need to add the datetime stamp to the 'duration' span, and then we can have moment.js pick up on it, and render the duration, rather than relying on the value from the server, which is outdated when the cache is stale/

[SirRawlins]

We actually already have some JS which we can lean on for this:

https://github.com/sorry-app/theme-whitelabel/blob/master/src/javascripts/status-page.js#L18

So we should just be able to wrap the "duration" in a tag with the appropriate class and it'll render as a duration.

[SirRawlins]

Actually, the duration JS we already have can't be used, as it expected a fixed duration, which is what we're trying to avoid. We want something which calculates the duration/distance of time in words from a fixed DateTime.

[SirRawlins]

I think I might replace the existing JS for a new one which will handle both duration and DateTime strings.

The duration can be described using the ISO format which it appears that Moment.js can parse.

This will DRY the existing code up a little, and also mean we can use some markup which will work for both past and present notices.

[SirRawlins]

After playing around with some JS ideas, they all felt a bit hacky.

After some discussions internally, we've decided to drop 'duration' from current incidents, so it's only available once static on old notices, which resolves our conflict with the cache.

I've updated the app so that duration() now returns nil for present notices, so we can make it's output conditional on the page.

[SirRawlins]

This has now been released in 2.46.0