Don't hide single columns on mobile tables

Summary: This handles whitespace differently on tables for phones. Fixes T3637

Test Plan: Test a History Table, able to scroll entire message.

Reviewers: epriestley

Reviewed By: epriestley

CC: Korvin, epriestley, aran

Maniphest Tasks: T3637

Differential Revision: https://secure.phabricator.com/D8011