Fix the python build that I broke

[K20shores]

• Uses the setup.py from the pybind11 cmake example
• Adds the python test to the suite of cmake tests so that they can be run from any computer

Instructions

Installing the musica python package

mkdir build
cd build
pip install -e ..

Building and testing with cmake

mkdir build
cd build
cmake -DMUSICA_ENABLE_PYTHON_LIBRARY=ON ..
make
make test ARGS=--verbose