R1:1b7f04914c2c

Make AphrontErrorView work on devices

Summary:
This is the last Paste UI element that doesn't work properly on tablets/phones. Make it flexible.

Also add empty states to Paste.

Test Plan: Viewed various errors, and `/uiexample/errors/`.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Differential Revision: https://secure.phabricator.com/D3429