Support Pagination for namespace list

The rest api metadefs/namespaces supports pagination using the parameters
of limit, marker, sort_dir, & sort_key. However, the glance client isn't
passing those parameters through (they come in as kwargs). This is
preventing pagination from working properly in horizon.

This is affecting Horizon support: https://review.openstack.org/#/c/104063/

Change-Id: Ib349cf3a3a437eb1711f350b37d0bd0e7d01330a
Closes-Bug: 1381816