pythonPackages.pytestpep8: Move to own file and add version

pkgs/development/python-modules/pytest-pep8/default.nix

@@ -0,0 +1,28 @@
+{ stdenv, buildPythonPackage, fetchPypi
+, pytest, pytestcache, pep8 }:
+
+buildPythonPackage rec {
+  pname = "pytest-pep8";
+  version = "1.0.6";
+
+  src = fetchPypi {
+    inherit pname version;
+    sha256 = "06032agzhw1i9d9qlhfblnl3dw5hcyxhagn7b120zhrszbjzfbh3";
+  };
+
+  buildInputs = [ pytest ];
+  propagatedBuildInputs = [ pytestcache pep8 ];
+
+  checkPhase = ''
+    py.test
+  '';
+
+  # Fails
+  doCheck = false;
+
+  meta = with stdenv.lib; {
+    license = licenses.mit;
+    homepage = https://pypi.python.org/pypi/pytest-pep8;
+    description = "pytest plugin to check PEP8 requirements";
+  };
+}