README update

[nickrusso42518]

Should describe install Makefile target

[pdice]

I don't think the Makefile approach is consistent with a python based project.

Instead I would expect to be doing:
python setup.py build
python setup.py install

I'd follows this:
https://github.com/pypa/sampleproject
https://packaging.python.org/tutorials/packaging-projects/

[nickrusso42518]

I'm willing to be open minded, but I'm not sure that's appropriate for a consumable utility. The "setup" here is just installing other Python packages, not actually treating this repo as if it were a Python package. Also those commands are 5x more typing than make which is what I use to regression test my changes. If you want to retool the project on a dev branch with this new method after using it for some testing on your end, I'd be happy to talk it over. I think you'll dig the Makefile if you give it a chance.