associate feed items with author

When simplefeed runs, it runs through cron generally and feed items are created with the super user instead of the user that owns the feed (and persumably the feed items). We should make this happen using the psuedo code:

$user = user_load(array('uid' => $feed->uid));
// run drupal_execute_form()
// Load the anonymous user to prevent other strange errors
$user = drupal_anonymous_user();

Needs to be tested but this way if a user adds a blog, cron runs and grabs items, and user goes to delete their blog, all of those items should still be deleted since they are owner of it.