First pass at visual treatment for "general info"

* Wire in data from the ``statistics`` worksheet to highlight
  stand-out statistics.
* Move charges by category chart to "General Info" section
* Add icons from the noun project. These are referenced in the
  spreadsheet.
* Add jQuery snippet to define popovers for terms that we want
  to define.  To use, wrap the word in
  ``<span data-term='term-key'><span>`` where ``term-key``
  corresponds to a key in the ``glossary`` worksheet.  To support
  this functionality, I had to update the Tarbell config to
  generate data.json.
* Use Jinja includes to combine task-specific stylesheets into
  ``css/convictions.css``.
Add age chart

Add JavaScript to render a chart of convictions by age.

Add a ``warnings`` worksheet to the Tarbell spreadsheet and show
this in the template.
Add mockup of crimes affecting women disparity graphic
Remove unintended blockquotes
Remove more blockquotes
Add mock graphic separators

To illustrate where we're putting graphic elements, add an
example of a courtroom sketch and gray separator bars.

I think the graphic elements look better if they take up the full
viewport width, so remove the padding from the body and instead
use the class column in the Tarbell spreadsheet to add the
Bootstrap ``container`` class.

Break the graphic elements into their own "slides" so they can
be contstrained within a container or take up the full width at
our discretion.
Merge pull request #72 from bepetersn/two-tier-nav

Basic two tier nav
Merge branch 'master' into two-tier-nav

Integrate some of my layout changes with @bepetersn's nav
templating.

I couldn't get the num_slides macro to work.  The extension that
provides the ``do`` keyword wasn't loaded and I wasn't sure how
to do this within Tarbell.  It was easy enough to just iterate
through the slides and use an ``if`` statement.

Also update ``index.html`` to render nested sections for both
the top-level and slide elements.

Make the circles links to the slides.

Conflicts:
	css/simple.css
	slides/intro.md
modularize css; get rid of 'blah'
navigation functional