In PHUIInfoView, only show list UI if more than 1 item
Summary: We often just setError as an array even if it's only one error. This just makes the UI a little cleaner in these cases.
Test Plan: Remove all reviewers from a diff, see status error without list styling.
Reviewers: epriestley
Reviewed By: epriestley
Subscribers: Korvin
Differential Revision: https://secure.phabricator.com/D14308