Add fluid-view as an option for PHUIDocumentView
Summary: Fixes some UIExample UI issues, adds a new full-width setting for DocumentView
Test Plan:
Test UIExamples at desktop and mobile breakpoints
{F327446}
Reviewers: btrahan, epriestley
Reviewed By: epriestley
Subscribers: Korvin, epriestley
Maniphest Tasks: T7431
Differential Revision: https://secure.phabricator.com/D11933