Twenty Fourteen: fix Ephemera Widget to avoid showing full post content when...

Twenty Fourteen: fix Ephemera Widget to avoid showing full post content when displayed in single post or page. Restore the global `$more` to its original value after the widget output to avoid any issues caused by changing a global variable.

Props obenland, mor10, Frank Klein. See #26961.
Built from https://develop.svn.wordpress.org/trunk@27124


git-svn-id: https://core.svn.wordpress.org/trunk@26991 1a063a9b-81f0-0310-95a4-ce76da25c4cd