background folder has never been used for GNU social

.gitignore

@@ -1,5 +1,4 @@
 avatar/*
-background/*
 files/*
 file/*
 local/*

lib/default.php

@@ -140,11 +140,6 @@ $default =
               'path' => $_path . '/avatar/',
               'ssl' => null,
               'maxsize' => 300),
-        'background' =>
-        array('server' => null,
-              'dir' => INSTALLDIR . '/background/',
-              'path' => $_path . '/background/',
-              'ssl' => null),
         'public' =>
         array('localonly' => false,
               'blacklist' => array(),

lib/installer.php

@@ -133,7 +133,7 @@ abstract class Installer
         }
 
         // Check the subdirs used for file uploads
-        $fileSubdirs = array('avatar', 'background', 'file');
+        $fileSubdirs = array('avatar', 'file');
         foreach ($fileSubdirs as $fileSubdir) {
             $fileFullPath = INSTALLDIR."/$fileSubdir/";
             if (!is_writable($fileFullPath)) {