Log Message:
www/ruby-loofah: update to 2.2.2

## 2.2.2 / 2018-03-22

Make public `Loofah::HTML5::Scrub.force_correct_attribute_escaping!`,
which was previously a private method. This is so that downstream gems
(like rails-html-sanitizer) can use this logic directly for their own
attribute scrubbers should they need to address CVE-2018-8048.