utils: Move functionality from storage.misc

move persistFile into utils

Change-Id: I2c547e3ac2ecf19359c32f7e717ad7b098bfbca4
Signed-off-by: Yeela Kaplan <ykaplan@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/31583
Reviewed-by: Yaniv Bronhaim <ybronhei@redhat.com>
Reviewed-by: Nir Soffer <nsoffer@redhat.com>
Reviewed-by: Allon Mureinik <amureini@redhat.com>
Reviewed-by: Antoni Segura Puimedon <asegurap@redhat.com>
Reviewed-by: Dan Kenigsberg <danken@redhat.com>