Move namePrefix="" python packages out of python-packges.nix

It doesn't make sense to build tools/applications with three different
python interpreter versions, so move them out of python modules list.

Also reverts 53ffc6e0ef.

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

@@ -0,0 +1,13 @@
+{ stdenv, fetchurl, pythonPackages }:
+
+pythonPackages.buildPythonPackage rec {
+  name = "rbtools-0.4.1";
+  namePrefix = "";
+
+  src = fetchurl {
+    url = "http://downloads.reviewboard.org/releases/RBTools/0.4/RBTools-0.4.1.tar.gz";
+    sha256 = "1v0r7rfzrasj56s53mib51wl056g7ykh2y1c6dwv12r6hzqsycgv";
+  };
+
+  propagatedBuildInputs = [ pythonPackages.setuptools ];
+}