Bug 9016: DB changes: new table overduerules_transport_types

Bug 9016: DB changes: new table overduerules_transport_types

This patch adds:
- a new table overduerules_transport_types.
- a new column letter.message_transport_type.
- a new primary key for letter.
- fill the new table with existing values.

Test plan:
After applying this patch and executing the updatedatabase entry, verify
that the overduerules_transport_types table contains a row for each
entry in the overduerules table.
The message_transport_type column should contain 'email'.

Signed-off-by: Olli-Antti Kivilahti <olli-antti.kivilahti@jns.fi>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>