hostname: Fix hostname syntax validation
hostname: Fix hostname syntax validation

Change-Id: I9fac1626018837df8fd6170ac9bdab4bc67270e7
Bug-Url: https://bugzilla.redhat.com/1366270
Signed-off-by: Simone Tiraboschi <cb03129c66ba4da7ba7044049d0f43907bf857bb@redhat.com>

oVirt/ovirt-setup-lib,oVirt/ovirt-setup-lib,oVirt/ovirt-setup-lib,oVirt/ovirt-setup-lib