Fixes ruby 2.0.0 compilation on Darwin.
Use the recommended http://cache.ruby-lang.org host to get the ruby archives
Updates ruby 1.9.3 to patch-level 484. Fixes CVE-2013-4164
Updates ruby 2.0.0 to patch-level 353. Fixes CVE-2013-4164
Updates ruby 1.8.7 to the latest patch-level. WARNING: unsupported

ruby 1.8 should be phased out as it contains security issues and is
unsupported by the ruby core team. This is the last update available but it
doesn't fix all CVEs.
Re-instate the "hydraPlatforms = []" setting accidentally overwritten earlier.
haskell-HDBC-odbc: re-generate with cabal2nix
haskell-scientific: re-generate with cabal2nix
haskell-codec-image-devil: re-generate with cabal2nix
Re-generate cuda-related expressions with recent version of cabal2nix.