Remove setuptools from install_requires.

We already import setuptools in setup.py so its not necessary
to explicitly list it. Also, it apparently prevents users from
upgrading using distribute.

Thanks to Jannis Leidel for the report.

THANKS

@@ -19,3 +19,4 @@ Travis Cline <travis.cline@gmail.com>
 Adrien Lemaire <lemaire.adrien@gmail.com>
 Oliver Tonnhofer <olt@bogosoft.com>
 Anand Chitipothu <anandology@gmail.com>
+Jannis Leidel <jannis@leidel.info>

setup.py

@@ -42,8 +42,6 @@ setup(
     packages = find_packages(exclude=['examples', 'tests']),
     include_package_data = True,
     
-    install_requires=['setuptools'],
-
     entry_points="""
     
     [console_scripts]