Let ExoneraTor only serve completed dates

While investigating ExoneraTor downtimes (legacy/trac#24534 (moved)) we noticed that a large number of requests are being made for the current date. It seems that somebody is using ExoneraTor as some sort of exit list interface.

That's not what ExoneraTor is designed for, and it's not what it's good at. We also cannot guarantee that ExoneraTor provides correct results, because the import may well be behind a few hours, which typically doesn't matter.

We should reject requests for the current day and for the day before.

I'll attach a possible patch shortly.

Regarding translations, let's finalize the text in English and then wait a few weeks for Transifex translators to provide translations. It should be sufficient to verify them using Google Translate.