New scrapers and readability fallback extractor

The highlights of this release are the addition of a number of new news source scrapers, and particularly the addition of a fallback headline and text extractor based on the readability language. This means that, even if the site being scraped serves up an unknown page format, we can attempt to extract the body text and headline using heuristics.

A number of bug fixes are also included.

First release, for content pilot project

v1.0.0

First release, for data collection pilot