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`.
Yeah yeah, I want parallel glob expansion but you get what I mean.
These two packages like getting upgraded together so to minimize
incompatibilities I'm upgrading them both in the same commit.
