Towards #856

* As necessitated by the meaningless tracker blocker check
  in Panopticlick using a “simulated tracker domain” that
  begins with “tracker”.

It looks like the stats for a regular local inquiry
were based on the previous inquiry that used the
news sites domains.

Closes #423

Added an empty line to the ends of all tracker entries so that the resulting HTML will properly close off the list in the Notes section and validate. Closes builder#99. Progress towards themes#156.

Transformed existing content to use the shorthand Blockdown format whenever possible. Related to builder#103.

Updated all existing content with link to the Ethical Design Manifesto. Progress towards better/themes#111.

Removed clouds section and moved entries to trackers. The prevalence statistics are currently broken.

Updated prevalence template tags so that they’re on their own lines so the markdown parser doesn’t choke on them.