Use another Api endpoint that helps the lister to be stateful.
The Api endpoint used needs a ``since`` value that represents a
sequential index in the history.
The ``all_packages_count`` state helps in storing a count which will be
used as ``since`` argument on the next run.
The Elm Lister lists Elm packages origins from the Elm
lang registry.
It uses an http api endpoint to list packages origins.
Origins are Github repositories, releases take advantages
of Github relase Api.