Scribe Content Cleaner plugin

Formats the content of the HTML wrapped by the Scribe instance and applies Guardian rules for cleaning content to a standard format.

Rules summary

Reduce multiple whitespace to a single space
Turns -- into the endash character, regards of spacing around the double-hyphens
Turns - into the endash character
Removes elements that only consist of break return elements
Reduces multiple break-returns to a single break return
Where a break-return separates non-boundary characters the break-return is replaced with a space

Tests are not running locally on Firefox due to an out-of-date Selenium Webdriver dependency