conf: examples in usage message
conf: examples in usage message

Added examples of command invocation in description
help message, aligned with man page.

Change-Id: I61932a0bb9cf2f14537e91470b1222cac13fe77c
Bug-Url: https://bugzilla.redhat.com/887566
Signed-off-by: Sandro Bonazzola <fcb014d63786651910af5db2ecc5316c668188ef@redhat.com>

oVirt/ovirt-image-uploader,oVirt/ovirt-image-uploader,oVirt/ovirt-image-uploader