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``.