pkgs/build-support/cabal: disable doCheck by default on GHC 7.0.x platforms

Trying to run the unit tests with GHC 7.0.4 causes so many builds to
fail that it's probably not worth-while.
haskell-editline: add old version 0.2.1.0
Fix build of haskell-platform 2009.2.0.2.
release-haskell.nix: configure package set for ghc 6.10.4, 6.12.3 and 7.0.4
Merge branch 'master' into haskell.