This library provides a handful of chainable HTML filters to
transform user content into markup. A filter takes an HTML
string or Nokogiri::HTML::DocumentFragment, optionally
manipulates it, and then outputs the result.
In preparation for gitlab 11.7 upgrade switch rails4 to rails50.
If required upgraded version to work correctly with rails50.
Fixed some cosmetic issue to make portlint happy.
Reviewed by: sunpoet
Differential Revision: https://reviews.freebsd.org/D18957