Conpherence - tweak file display

Summary: using chrome and safari and the mighty "YAYAYAYAYAYAYAYAYAYAYAYAYAYAYAYAYAYAYAYAYAYAYA.gif", tweak _shorten and CSS to get display just right

Test Plan: will upload screenies

Reviewers: epriestley, chad

Reviewed By: epriestley

CC: aran, Korvin

Maniphest Tasks: T2399

Differential Revision: https://secure.phabricator.com/D5383