Try setuptools first, then fallback to distutils

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 `install_requires` field, 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's a safe approach.