pythonPackages.pyechonest: Move to own file

Also disable on Py3k due to syntax errors.

(cherry picked from commit 85e3b5bd41ff691022b40669800b1a0127c25a0d)

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

···
+{ stdenv, buildPythonPackage, fetchPypi, isPy3k }:
+
+buildPythonPackage rec {
+  pname = "pyechonest";
+  version = "8.0.2";
+  disabled = isPy3k;
+
+  src = fetchPypi {
+    inherit pname version;
+    sha256 = "496265f4b7d33483ec153b9e1b8333fe959b115f7e781510089c8313b7d86560";
+  };
+
+  meta = with stdenv.lib; {
+    description = "Tap into The Echo Nest's Musical Brain for the best music search, information, recommendations and remix tools on the web";
+    homepage = https://github.com/echonest/pyechonest;
+  };
+}

pkgs/top-level/python-packages.nix

···
 
   py4j = callPackage ../development/python-modules/py4j { };
 
-  pyechonest = self.buildPythonPackage rec {
-    name = "pyechonest-8.0.2";
-
-    src = pkgs.fetchurl {
-      url = "mirror://pypi/p/pyechonest/pyechonest-8.0.2.tar.gz";
-      sha256 = "496265f4b7d33483ec153b9e1b8333fe959b115f7e781510089c8313b7d86560";
-    };
-
-    meta = {
-      description = "Tap into The Echo Nest's Musical Brain for the best music search, information, recommendations and remix tools on the web";
-      homepage = https://github.com/echonest/pyechonest;
-    };
-  };
+  pyechonest = callPackage ../development/python-modules/pyechonest { };
 
   billiard = buildPythonPackage rec {
     name = "billiard-${version}";