Explicitly specify Pygments 1.6 for Chef recipes.

Hi @runemadsen,

Either today or tomorrow, I'm going to be upgrading O'Reilly's Production toolchain from Pygments 1.5 to Pygments 1.6. Related to that, I thought it might be a good idea to explicitly specify the installation of Pygments 1.6 in our Chef recipes.

Pygments 1.6 is actually being installed already (because it's currently the default via easy_install), but for the future, I think that it's good to maintain the version number explicitly in Chef, so if we reprovision the full box, for example, it doesn't upgrade us to 1.7 before we're ready.

Thanks,
Sanders