Improve copy/paste from Diviner, in Phabricator

Summary: Change CSS style name from code to pre. This depends on D2067.

Test Plan: Viewed the html from Firefox

Reviewers: epriestley

Reviewed By: epriestley

CC: jungejason, aran

Maniphest Tasks: T207

Differential Revision: https://secure.phabricator.com/D2068