python: Issue #15: Cython needs to be in setup_requires

We need Cython BEFORE installing kmod (done with setup_requires),
and AFTER installation - during runtime (done with install_requires)
diff --git a/libkmod/python/setup.py b/libkmod/python/setup.py
index 2e15d03..f105782 100644
--- a/libkmod/python/setup.py
+++ b/libkmod/python/setup.py
@@ -15,7 +15,6 @@
 # You should have received a copy of the GNU Lesser General Public License
 # along with python-kmod.  If not, see <http://www.gnu.org/licenses/>.
 from setuptools import setup
-from distutils.core import setup
 from distutils.extension import Extension as _Extension
 import os as _os
 import sys as _sys
@@ -62,4 +61,5 @@
     cmdclass = {'build_ext': build_ext_workaround},
     ext_modules=ext_modules,
     install_requires=["Cython"],
+    setup_requires=["Cython"],
     )