Diffusion browser: Update editor link when clicking on a line

Summary: Highlighing and URL are fixed on click - now the edit button too.

Test Plan: click on lines with and without value in "Editr Link" (And without %l in it).

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D9227