use chef environments for pydotorg

[benjaminws]

This has been weighing heavily on my mind since I did it, so I need to let it out and confess. I didn't use chef's environments on purpose, because it was easier to just use an attribute.

It won't take a whole lot to get it using environments. I'll try to get to that this week at some point. This will also help solve things like #110

Tasks off the top of my head:

• make current_env become node.chef_environment see https://github.com/python/psf-chef/blob/master/cookbooks/pydotorg-redesign/recipes/default.rb#L4
• make sure there are a prod and staging environment
• make sure the nodes are in the right environment
• pin version lines to prod and staging environment

TBD: what versions on what env?

[coderanger]

That should be node.chef_environment, it isn't an attribute.

[benjaminws]

Fixed. Muscle memory is tragic.