[WIP] Added setup.py.  

`python setup.py install` now calls cmake, and make and installs python package csympy.  It works but it's missing some info and may need some better error handling/checking.  Addresses half of #160
That would be simpler but if we set WITH_PYTHON then csympy is compiled outside of the setup.py script.  I think to test that setup.py correctly compiles csympy it should be done separately.