Update dbf-import.php to include Memo.php

[adanielvv]

Fixes this error:

PHP Fatal error:  Uncaught Error: Class 'XBase\Memo' not found in ~/php-xbase/src/XBase/Table.php:35
Stack trace:
#0 ~/DBFToMySQL/dbf-import.php(42): XBase\Table->__construct('~/dbffile...')
#1 ~/DBFToMySQL/dbf-import.php(24): dbftomysql('DBFFILE.dbf')
#2 {main}
  thrown in ~/php-xbase/src/XBase/Table.php on line 35

[vjardin]

This patch is needed. Please, can you pull it?