Overhaul NB Conversion and Add Matlab Notebooks

Woohoo!

Take a look at the following notebooks:
http://nbviewer.ipython.org/github/blink1073/numerical-tours/blob/master/python/todo/audio_1_processing.ipynb
http://nbviewer.ipython.org/github/blink1073/numerical-tours/blob/master/matlab/notebooks/audio_1_processing.ipynb

With the new layout, the user can download the github blob (see the install instructions in the notebook), and have everything they need to run the Matlab or Python notebooks.  The new Python directory layout is:

- python
    - solutions
        - audio_1_processing.py
        - etc.
    - audio_1_processing.ipynb
    - etc.
    - nt_toolbox.py <- this could eventually be moved to a package `nt_toolbox`