bug fix for MDB2 in LiveUser

I just found another issue now with the updated MDB2 here was my error

Error: Call to undefined function: MDB2_Driver_mysql::exec(). in 
/Volumes/DATA/www/classes/PEAR/MDB2.php at line 1642
  (/Volumes/DATA/www/classes/PEAR/MDB2.php)
  (/Volumes/DATA/www/classes/PEAR/LiveUser/Admin/Storage/MDB2.php)
  (/Volumes/DATA/www/classes/PEAR/LiveUser/Admin/Storage/SQL.php)
  (/Volumes/DATA/www/classes/PEAR/LiveUser/Admin/Auth/Common.php)
  (/Volumes/DATA/www/classes/PEAR/LiveUser/Admin.php)

I worked out the exec method in the storage was trying to call an 
unknown method exec, changing it to query worked so i will go with this 
for now.

function exec($query)
     {

         $result = $this->dbc->query($query);
         if (PEAR::isError($result)) {
             $this->_stack->push(
                 LIVEUSER_ADMIN_ERROR_QUERY_BUILDER, 'exception',
                 array('reason' => $result->getMessage() . '-' . 
$result->getUserInfo())
             );
             return false;
         }
         return $result;
     }