Use 'ffs' rather than 'ext' for the 'SR for openstack'

This is needed because the xcp-sm 'ext' needs whole disks, and
can't use parts of existing filesystems.

Fixes #30

Signed-off-by: David Scott <dave.scott@eu.citrix.com>
networkscripts: Remove unused 'mgmt' variable

Signed-off-by: Euan Harris <euan.harris@citrix.com>
Merge pull request #32 from djs55/merge

a couple of bugfixes