Bug 13803 Flag to self check book has gone into transit

Bug 13803 Flag to self check book has gone into transit

Ensure that the transit flag (in field CV) is set
if return message is 'wasTransfered'

CV is being set for other return conditions but not for
wasTransfered [sic] The presence of this flag is required to
route returns to the correct bin if the SC unit is so
enabled

Signed-off-by: Frederic Demians <f.demians@tamil.fr>
  I agree with the solution to an issue I've already encountered and
  patched localy that way. It would be nice to have a better doc of
  C4::Circulation::AddReturn in order to see immediately that
  WasTransfered is a valid feedback for a check-in.

Signed-off-by: Brendan Gallagher <brendan@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>