accessor for finding the latest version of an Application
changing appcast URL from id to a new slug field
makes for much nicer URLs
adding Markdown dependency
fixing release_notes_display to output a safe string
adding help text to the version strings
(I keep forgetting which is which)
nicer and configurable upload URLs
replacing `active` and `published` fields with `created` and `publish_date` fields
`created` replaces the incorrectly-named `published` field and is just for developer information
`publish_date` replaces the `active` field: only such versions that have a `publish_date` in the past are considered active. This allows for scheduled update publishes.
adding and using prepared version query
DRY!
fixing a silly mistake: forgot to call the function
version bump and documentation update