haskell-packages.nix: cosmetic
haskell-GLUT: update to version 2.5.0.1
haskell-packages.nix: disable transformers 0.3.0.0 when building with GHC 7.7 or later

It's a core package now.
haskell-packages.nix: update 'cgi' to version 3001.1.8.4 when building with GHC 7.7 or later

Not that it helps much ... the package depends on MonadCatchIO-mtl, which is
broken in the latest version of GHC.
haskell-packages.nix: enable dynamic linking in GHC 7.7 or later

The current snapshot requires shared libraries to be built (otherwise
some packages won't build). I'm sure that's a mistake in the way it's
configured that should be fixed. Anyway, enabling shared library support
is an easy way out (and an interesting experiment).
cabal-install: jailbreak version 1.18.0.2 to fix the build with GHC 7.7 or later
async: jailbreak version 2.0.1.4 to fix the build with GHC 7.7 or later