Turn post thumbnail support off by default, as it's used nowhere in the theme by default. Also add a DocBlock into the theme which gives more information on post thumbnail support implementation.
_s: Removes unnecessary switch in and out of PHP.
Merge branch 'master' of https://github.com/Automattic/_s.git
Remove  title attributes where it duplicates  in anchor text. See http://core.trac.wordpress.org/ticket/24203.
Merge pull request #209 from Automattic/remove-redundant-title-attributes

Remove `the_title_attribute` title attributes where it duplicates `the_title` in anchor text. See http://core.trac.wordpress.org/ticket/24203.
DocBlock adjustments to post thumbnail support. See #207.
Merge pull request #207 from Automattic/post-thumbnails-off-by-default

Turn featured thumbnail support off by default.