Fixed packaging issue caused by ez_setup.py

ez_setup.py is not packaged with the rest of the code, this causes
`easy_install gitpython` to fail with an ImportError.

ez_setup is useful when setuptools are not present in the pythonpath.
(cherry picked from commit e7c37c6e0b12d2b4f5001fb3ecfc250a682f6d57)

Author: ctrochalakis

setup.py

@@ -1,6 +1,10 @@
-from ez_setup import use_setuptools
-use_setuptools()
-from setuptools import setup, find_packages
+try:
+    from setuptools import setup, find_packages
+except ImportError:
+    from ez_setup import use_setuptools
+    use_setuptools()
+    from setuptools import setup, find_packages
+
 from distutils.command.build_py import build_py as _build_py
 from setuptools.command.sdist import sdist as _sdist
 import os