rescan-scsi-bus.sh should be used when available

[Lee Yarwood]

rescan-scsi-bus.sh packaged as part of the sg3_utils by most distributions provides a more robust method of scanning the SCSI bus for new or changes to existing LUNs on a system over the current method used in os-brick [1].

[1] https://github.com/openstack/os-brick/blob/master/os_brick/initiator/linuxfc.py#L35

[Walt Boring (walter-boring)]

When this code was originally written, that shell script wasn't part of the standard packages included by ubuntu. I'd rather not rely on something that hasn't existing in older releases of the distros.

[Lee Yarwood (lyarwood)]

As the title suggests I wasn't looking to replace the current method, just to use the script when it is present on a system. I had completely forgotten about this until it was closed out but if you think that approach is any better I'd be happy to post patches this cycle.