Remove top-level dbus_python and pythonDBus.

See #11567.

Furthermore, it renames pythonPackages.dbus to pythonPackages.dbus-
python as that's the name upstream uses.

There is a small rebuild but I couldn't figure out the actual cause.

pkgs/applications/misc/printrun/default.nix

@@ -11,7 +11,7 @@ python27Packages.buildPythonApplication rec {
   };
 
   propagatedBuildInputs = with python27Packages; [
-    wxPython30 pyserial dbus psutil numpy pyopengl pyglet cython
+    wxPython30 pyserial dbus-python psutil numpy pyopengl pyglet cython
   ];
 
   doCheck = false;