Try setuptools first, then fallback to distutils to take advantage of automated installation

While installing you can see this warning message:
> /usr/lib/python2.7/distutils/dist.py:267: UserWarning: Unknown distribution option: 'install_requires'

Since distutils does not support the [nice](http://pythonhosted.org/setuptools/setuptools.html#declaring-dependencies) `install_requires` keyword, it is not able to download and auto-install a package to resolve dependencies.

This changes adds support to setuptools and falling back to distutils, it is a safe approach.