#3 Deleted support for verb ListIdentifiers

[Mark Lindeman]

In the default Backend
(OAI/Server/Backend/Default/Backend.php) the method
listIdentifiers has no support for Deleted records.
There is a test in this method that looks for the
column $this->oai['deleted_record'], but that column is
not in the Select statement.
Fix:
add $this->options['deleted'] to the var $query.