osd_login: Add autologin script for objlayoutdriver

From: Sachin Bhamare <sbhamare@panasas.com>

This script is part of the autologin feature mandated by the
pnfs-objects standard.
It is called from objlayoutdriver.ko in the kernel.

It invokes iscsiadm program to perform the iscsi login to OSDs.
It also features a watchdog which will make sure that control
returns to kernel after 15s timeout.

Signed-off-by: Sachin Bhamare <sbhamare@panasas.com>
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
Signed-off-by: Steve Dickson <steved@redhat.com>