Addressing CVE-2019-17109
Also added missing description, homepage & license. Re-disabled for py3k
as the kojira executable doesn't seem to be happy with it.
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`.