[CONTACT] reduced diff with OCB and official branch: now simply use partner_id as the sale order contact
[CONTACT] fixed typo
[CONTACT] propagate order contact to invoice contact
[CONTACT] sale order contact is now simply partner_id
[CONTACT] adapted test for RS-OCB
[CONTACT] adapted test for RS-OCB
[CONTACT][TRAVIS] now running Travis tests with --test-enable  for the modules changed by RS-OCB