use default configuration file for pdisk backend
PDisk’s public IP should be set in the new image manifest and in the notification email to the user.
in the notification email the image validity should be in days.
set sender email on the new image notification email.
No need to rescan iSCSI sessions from the TM - it’s done from the stratus-pdisk-client.py. Instead make discovery of the targets on the iSCSI portal.
minor
allow to define hostname of the backend for the PDisk service.