Slightly modified from a patch by lpeterse.
This change should work properly now with pandoc 220.127.116.11. It was broken with pandoc 1.5 due to a problem in pandoc.
This way we have a uniform solution for GHC 6.10 and 6.12, and don't have to use CPP tricks. This change fixes categories on GHC 6.12. Resolves Issue #98.
This reverts commit c63fec0. Conflicts: Network/Gitit/ContentTransformer.hs