setup.py: support both distutils and setuptools

setuptools is preferred if installed. allows running in 'develop' mode
(e.g. python setup.py develop)

Author: jtriley

Diff for: .gitignore

@@ -5,3 +5,4 @@
 MANIFEST
 build
 dist
+*.egg-info

Diff for: setup.py

@@ -24,10 +24,10 @@
 """
 Standard build script.
 """
-
-import sys
-import os
-from distutils.core import setup
+try:
+    from setuptools import setup
+except ImportError:
+    from distutils.core import setup
 
 
 setup(name = "github",