Add rowId to fix an issue when importing file in Access

When importing a file generated by Seine into Access (only tested with 2010),
Access was complaining and the following error was displayed:
"Unexpected error from external database driver (1)"

=> Adding the row ID to the sheet1.xml file fixes the issue.
Merge pull request #1 from adrilo/fix_issue_with_access_import

Add rowId to fix an issue when importing file in Access