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/pycryptodome/default.nix

@@ -1,12 +1,11 @@
-{ stdenv, fetchurl, python, buildPythonPackage, gmp }:
+{ stdenv, fetchPypi, python, buildPythonPackage, gmp }:
 
 buildPythonPackage rec {
   version = "3.6.2";
   pname = "pycryptodome";
-  name = "${pname}-${version}";
 
-  src = fetchurl {
-    url = "mirror://pypi/p/pycryptodome/${name}.tar.gz";
+  src = fetchPypi {
+    inherit pname version;
     sha256 = "b19ed0f7752a0b1ec65834c9acb02ba64a812990854e318d32a619c709b14a69";
   };