cekees/add cgal python

Added  the CGAL python bindings. The cmake-based  install is a little strange, but this is  working for me. @johannesring these might be useful for fenics. I'm guessing CGAL is mainly useful from C++, but I'm exploring the python bindings.
But this is part of the python package:
```
profile_links:
  - name: python_binaries
    before: everything
    launcher: 'bin/*'

  - name: python_packages
    link: 'lib/python{{pyver}}/site-packages/*'
    dirs: true

  - name: python_exclude
    after: python_packages
    before: everything

    exclude: 'lib/python{{pyver}}/site-packages/**/*'
```
So just depending in python should work, doesn't it?