Pyoctree

* Added numpy as a dependency
* Fixed readme rst formatting issue on PyPi

Release to address Issue 23, which includes:
* Modification to Intersection class to include the label of the intersected tri.
* New jupyter notebook Examples/pyoctree-intersection.ipynb to demonstrate how the intersected tri labels can be extracted and the tri face normals compared to the direction of the intersecting ray
* Added numpy as a dependency in setup.py (Issue 28)

- Sets default install to not use OpenMP to ensure maximum compatibility
- Adds install command line option that enables user to compile using OpenMP as long as C++ compiler supports it

* Python 3 compatible (>=3.5)
* Automatically sets compile and link options for openmp corresponding to current system (mscv, mingw32, unix supported)
* Fixed Python packaging related errors

- Modified manifest to include h files
- Modified setup.py to use setuptools so that a python wheel can be created

First release