Revert "add --index-url cli parameter"

This reverts commit f178c69f49762ae97e16ac3a751ee35422cfd74c.
Revert "make index_url an optional parameter to update()"

This reverts commit 7061dd795d1fdd6771430eacecd102d91ecb20b0.
Revert "make index_url an optional parameter for find_packages"

This reverts commit b722c2a68f6790cffc60ca8a404c12d1cd1d949c.