This reverts commit c8bc18bcc2.
Moving to staging - it's quite a large rebuild (7-8k per platform),
which probably wasn't noticed; the change doesn't seem urgent.
The `buildPython*` function computes name from `pname` and `version`.
This change removes `name` attribute from all expressions in
`pkgs/development/python-modules`.
While at it, some other minor changes were made as well, such as
replacing `fetchurl` calls with `fetchPypi`.