pythonPackages: remove name attribute`

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`.

pkgs/development/python-modules/buildout-nix/default.nix

@@ -1,12 +1,11 @@
-{ fetchurl, stdenv, buildPythonPackage }:
+{ fetchPypi, stdenv, buildPythonPackage }:
 
 buildPythonPackage rec {
   pname = "zc.buildout";
   version = "2.11.5";
-  name = "${pname}-nix-${version}";
 
-  src = fetchurl {
-    url = "mirror://pypi/${builtins.substring 0 1 pname}/${pname}/${pname}-${version}.tar.gz";
+  src = fetchPypi {
+    inherit pname version;
     sha256 = "537a22715d82362cddd811da08d11a31d30d5161ce7994b208bd85ebb348d122";
   };