Python motivation

This is a rough version of motivational slides for python - based on @sritchie73's R motivational slides.
Idea is that they would be presented at the beginning of a python lecture. Thoughts?
> +  <p class="fragment">
> +    Javascript or Ruby? <br>
> +    There are good numerical libraries and people are actively developing other packages and tools.
> +  </p>


And folks are certainly writing packages and tools for JavaScript and
Ruby.  I think the difference here is just the depth of numerical
libraries, which is likely due to the difference in the ease of
writing C extensions ;).