Change to use dash instead of slash

There is no known way to embed slashes into container names, even when
using URL escape sequences. Since it would seem that the more common
case would be some other character, we validate using a dash ('-')
character as the delimiter.

It should also be noted that the documentation for container listing,
found here:
http://docs.openstack.org/api/openstack-object-storage/1.0/content/s_listcontainers.html,
does not describe the use of the prefix or delimiter parameters.

DocImpact

Change-Id: Ie467a4181c6f64b24c82c72b70a37183d443dee1
Signed-off-by: Peter Portante <peter.portante@redhat.com>
Merge "Change to use dash instead of slash"