Adding collection of selected Notebooks

So far, slides support has been extended only to the first 4 lectures notes
First export of Notebooks to Slides

So far, HTML slides are only those referring to the first 4 lectures (i.e., 04_introducing_functions.slides.html). Other files are simple HTML pages.
Updated License
Index notebook has been renamed. The TOC notebook has been (slightly) updated.

The TOC notebook now contains a Code cell reporting comments describing the purpose of the "# Table of Contents (Slides)" Cell.
Notebooks Updated!!

- All notebooks are now ready to be generated as slides.
- TOC has been updated adding a reference to the `resources.ipynb` notebook.
- All notebooks now contain the correct link to the `Index.ipynb` notebook in the Navigation bar
Updated HTML Slides
Updated Instructions in README.md and added control script to convert and serve HTML slides of notebooks
Updated README.md instructions and removed License duplicate.