Bug 24296: Update stockrotation process to use branchtransfers.reason

Bug 24296: Update stockrotation process to use branchtransfers.reason

This patch updates all occurences of stockrotation related lookups of
branchtransfers status from using the 'comments' field to using the new
'reason' field.

Test plan:
1) Work through the process of creating a stock rotation plan and adding
   items to the plan.. no errors should be encoutered during this process.
2) Run the stockrotation cronjob to move some items on.. no errors
   should be encountered.

Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>