Phame - add some application polish.

Summary:
Fixes T4880. More specifically

 - adds an "edit" pencil to post lists iff you can edit the post
   - style change so this has no text-decoration
 - adds a "no data" box if you have no posts in a given view
   - style change to crush some margins so it formats like posts do
 - adds some validation that your configuration is correct if you are specifying a custom domain
 - updates docs about custom domains

Test Plan: clicked around and it was better! (see screenshots) read doc changes carefully

Reviewers: epriestley, chad

Reviewed By: epriestley

Subscribers: epriestley, Korvin

Maniphest Tasks: T4880

Differential Revision: https://secure.phabricator.com/D8918