Requiring setuptools > 3.3 for the replace=True option on working_set.add()

Perhaps older versions also support this option, but at least 0.7.2 does not.
So I picked the oldest version I had handy in my buildout egg cache...

setup.py

@@ -88,7 +88,7 @@ setup(
     package_dir = {'': 'src'},
     namespace_packages = ['zc'],
     install_requires = [
-        'setuptools>=0.7',
+        'setuptools>=3.3',
     ],
     include_package_data = True,
     entry_points = entry_points,
@@ -108,4 +108,3 @@ setup(
        'Topic :: Software Development :: Libraries :: Python Modules',
        ],
     )
-