downloads.haskell.org now moved

[Gershom B]

The migration of the downloads box to packet is now done.

Rather than uploading to downloads-origin.haskell.org, binaries should
now go to downloads-packet-origin.haskell.org. The former will be
decommissioned soon-ish. This applies for cabal and ghc binaries both.
Login for the `cabal` and `ghc` accounts on the box is sftp-only. Let
me know if there's any problems.

Cheers,
Gershom