downloads.haskell.org now moved

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