Support proxies with username and password for skeleton pypi
Support proxies with username and password for skeleton pypi

This uses the transport code from
https://gist.github.com/chrisguitarguy/2354951 (with some modifications),
which uses requests.

This should fix #109 for real this time.

ilastik/conda-build,mwcraig/conda-build,ilastik/conda-build,mwcraig/conda-build,rmcgibbo/conda-build,shastings517/conda-build,sandhujasmine/conda-build,takluyver/conda-build,takluyver/conda-build,frol/conda-build,rmcgibbo/conda-build,dan-blanchard/conda-build,sandhujasmine/conda-build,frol/conda-build,dan-blanchard/conda-build,ilastik/conda-build,rmcgibbo/conda-build,sandhujasmine/conda-build,shastings517/conda-build,frol/conda-build,mwcraig/conda-build,dan-blanchard/conda-build,shastings517/conda-build,takluyver/conda-build