setuptools upgrade is required on 10.6

during the saltstack step ...

```
==> Installing saltstack
==> Downloading https://pypi.python.org/packages/source/s/salt/salt-0.17.2.tar.gz
==> Downloading https://pypi.python.org/packages/source/p/pycrypto/pycrypto-2.6.tar.gz
==> /Library/Frameworks/Python.framework/Versions/2.7/bin/python setup.py install --prefix=/usr/local/Cellar/saltstack/0.17.2/libexec
==> Downloading https://pypi.python.org/packages/source/P/PyYAML/PyYAML-3.10.tar.gz
==> /Library/Frameworks/Python.framework/Versions/2.7/bin/python setup.py install --prefix=/usr/local/Cellar/saltstack/0.17.2/libexec
==> Downloading https://pypi.python.org/packages/source/p/pyzmq/pyzmq-14.0.0.tar.gz
==> /Library/Frameworks/Python.framework/Versions/2.7/bin/python setup.py install --prefix=/usr/local/Cellar/saltstack/0.17.2/libexec
==> Downloading https://pypi.python.org/packages/source/m/msgpack-python/msgpack-python-0.4.0.tar.gz
==> /Library/Frameworks/Python.framework/Versions/2.7/bin/python setup.py install --prefix=/usr/local/Cellar/saltstack/0.17.2/libexec
Traceback (most recent call last):
  File "setup.py", line 7, in <module>
    from setuptools import setup, Extension
ImportError: No module named setuptools
```

Used `pip` to upgrade an existing version of *setuptools 0.6c9* on test *OS X 10.6*.  For now, my install script forces the upgrade (`pip install setuptools --upgrade`) before running `brew install saltstack`.

Not sure if I edited this file right.  Just trying to help out with some of the leg work.  In my test, upgrading setuptools resolved the issue and saltstack successfully installed and communicated with the salt-master.