Workflow improvements when importing RSS then segmenting

[cavis]

Had a case where a feed was imported, and then days later, they went to mark a midroll. So:

1. Import RSS
2. Wait 1+ days
3. Go find an episode, change medium to Uncut, change segment_count 1 -> 2
4. Mark midroll, save

The weirdness was that:

• The uncut= logic in (3) doesn't trust original_urls older than 24 hours, so the filename of the Uncut ended up being a random guid (fallout from Preserve Uncut filenames #874)
• Some question if we should just start RSS imported episodes as Uncut
  • Would generate the waveform right away, and be immediately ready to add midrolls
  • Would take 2x the storage, esp if the user never plans to add midrolls to the back catalog
  • Imports would take a bit longer to complete (2x or more the porter processing)

Or middle of the road, make it a checkbox option on import?