recipes that are too big to fail

There are core recipes which are "too big to fail". These are recipes, if they are built incorrectly will cause systemic problems across the ecosystem. For example the recent move of some recipes to `noarch` could have caused problems with `conda` itself.

We need to have tighter control of these recipes.

I think that we need to (at least):
1. Have all (or at least some) of core as maintainers of these packages
1. Require review approval to merge