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/gplaycli/default.nix

@@ -3,8 +3,8 @@
 }:
 
 buildPythonPackage rec {
+  pname = "gplaycli";
   version = "3.21";
-  name = "gplaycli-${version}";
 
   src = fetchFromGitHub {
     owner = "matlink";