specify minimal setuptools version

Author: boegel

setup.py

@@ -111,7 +111,7 @@ def find_rel_test():
     test_suite="test.framework.suite",
     zip_safe=False,
     install_requires=[
-        'setuptools',
+        'setuptools >= 0.6',
         "vsc-base >= 2.4.18",
     ],
     extras_require = {