Revert "Handle __future__ imports in setup.py in skeleton pypi"

This reverts commit 9d5cae34adf5c5fa1a5c89cd756403a9ea8c3e91.
Better fix for __future__ imports in setup.py in skeleton pypi

See
https://github.com/conda/conda-build/commit/9d5cae34adf5c5fa1a5c89cd756403a9ea8c3e91.
Merge branch 'master' of github.com:conda/conda-build