using setuptools instead of distutils for packaging

setup.py

-from distutils.core import setup
+from setuptools import setup
 from ess import __version__
 
 setup(
@@ -8,6 +8,7 @@ setup(
     url="http://ess-bp.pages.esss.lu.se/ess-python-tools",
     author="Yngve Levinsen",
     author_email="yngve.levinsen@esss.se",
+    install_requires=["scipy", "numpy"],
     classifiers=[
         # How mature is this project? Common values are
         #   3 - Alpha