Bug 3638 : Captured Holds may need to generate a transfer

Bug 3638 : Captured Holds may need to generate a transfer

If a discharged item is captured for a hold at another branch
the selfcheck should generate a branchtransfer for it.
This was complicated as the checkin routine was setting its own
location from a field not set in many scm machines (e.g. 3M)
also in ILS::Transaction the test for location was incorrect
assuming that an empty string or undefined was a valid location

Signed-off-by: Chris Cormack <chris@bigballofwax.co.nz>
Signed-off-by: Paul Poulain <paul.poulain@biblibre.com>