Hide old blackouts

[ncmaas]

It doesn't really make sense to show a list of past blackouts, and they can really cause a lot of clutter. We should enable an option to hide / show old blackouts in the params. Possible exceptions would be for recurring blackouts, but I don't think that will really be a problem since the individual pieces of a set can more or less be handled independently.

[squidgetx]

We could also just add a rake task to delete old blackouts similar to how missed reservations are handled. I doubt that past blackouts are used or referenced even half as much as missed reservations might be

[orenyk]

Agreed, I can't think of a scenario where you'd need to look up an old blackout date.

[squidgetx]

closed via #690