Update PHUIObjectItemListView structure for more flexibility

Summary: Converts PHUIObjectItemView to use display: table rows and columns for more flexible layouts. Slightly increases spacing, improves mobile layouts. Fixes T5502

Test Plan: Tested in multiple applications and UIExamples. Ran through mobile, tablet, and desktop break points. Used IE8-IE10, Firefox, Chrome, Safari on both Mac and Windows.

Reviewers: btrahan, epriestley

Reviewed By: epriestley

Subscribers: Korvin, epriestley

Maniphest Tasks: T5502

Differential Revision: https://secure.phabricator.com/D10917