Enable version manifest unit test

The version manifest unit test needed to be adjusted
for gluster-swift.  Gluster-swift does not support a PUT
of an object "a" then another object "a/b".  The first object
"a" would be interpreted as a file, while "a/b" would
require "a" to now be a directory.

Change-Id: I1628d5575d1b68ccce20386a4a0a0b2442d631af
Signed-off-by: Luis Pabon <lpabon@redhat.com>
Reviewed-on: http://review.gluster.org/5987
Reviewed-by: Chetan Risbud <crisbud@redhat.com>
Reviewed-by: Peter Portante <pportant@redhat.com>
Tested-by: Peter Portante <pportant@redhat.com>
Rebase to proposed Havana DiskFile API

Change-Id: I767983f88c59786e30b6c64da16d1cb6ab3c3e7f
Signed-off-by: Peter Portante <peter.portante@redhat.com>