List setuptools dependency for completeness

setup.py

@@ -29,7 +29,7 @@ if sys.version_info[:2] < (2, 3):
     sys.stderr.write(msg)
     sys.exit(1)
 
-requires = ['meld3 >= 0.6.5']
+requires = ['setuptools', 'meld3 >= 0.6.5']
 
 if sys.version_info[:2] < (2, 5):
     # for meld3 (it's a distutils package)