Expose enabled state information

[mythmon]

Normandy records the history of enabled states of revisions, and exposes it in the UI. DC doesn't show this information anywhere, and it would be very useful.

[jcristau]

As release manager, knowing when an experiment or rollout did go live or was deactivated would be quite useful to correlate with other data sources, otherwise we have to rely on comments in bugs which will necessarily be incomplete and imprecise.

[peterbe]

I'll assume that @mythmon means; exposing this on a per-recipe details page basis.

However, spurred by @jcristau, I've always liked the idea of a "news feed" across all recipes. It should ideally have a clear timeline-looking feel so you can see what's happened today, yesterday, etc.

[peterbe]

Note-to-self; #47 is about showing more about the changes done on a recipe.