Refactor RSS generation and tweak inclusion rules

[jsvine]

With the anticipation of adding additional feeds, I figured I'd refactor the code we use to generate them, introducing a new method, generate_feed.

While doing that, I realized it'd be helpful to have slightly more specific rules for whether an entry is included, with the goals of:

• Including all entries less than X days old (based on date of discovery)
• Excluding entries more than Y days old
• Beyond that, setting a soft threshold of Z entries ...
• ... while not arbitrarily including only some portion of a group of inspections all discovered at the same time

[palewire]

As long as we're using the discovered date and not the inspection date I think this is fine. Over the last few weeks I've seen inspections discovered that are dated more than a month ago.

[jsvine]

Yep, sort order is:

• Discovered date first ...
• ... then inspection date
• ... then hash_id (just to keep things deterministic)

And yeahhhh, some of these get posted to APHIS quite a bit after the inspection dates. https://github.com/data-liberation-project/aphis-inspection-reports/issues/36 should help understand some component of that (i.e., how much of this is explained by reports themselves taking a long time to be finalized vs. finalized reports not being uploaded/released).

[jsvine]

(Oh, and yes, the max_age_days limit is based on the discovered date, not the inspection date.)

[palewire]

👍