In most places, the api-ref refers to the 'namespace_name' in URLs,
but in two places in the metadefs-namespaces-properties file, the
term 'namespace_id' is used. This patch fixes those two occurrences
in the interest of consistency, but also because it is causing a
warning that's interpreted as an error in the latest version of
os_api_ref [0].
[0] http://lists.openstack.org/pipermail/openstack-dev/2017-January/110606.html
Change-Id: I86435a216c9c8d8bd391fb662049662d7d303ae5
3a96347fe2