Swallow & report 404s from Swift (missing tenant)
Swallow & report 404s from Swift (missing tenant)

The 404s are caused when Keystone has a tenant that Swift does not.
These 404s can safely be ignored.
If not ignored, some meters are not collected from Swift, as the
ClientException stops the tenant loop from completing.

Change-Id: I34aa40ba6c8e40e6d51b0a8dd24b8975c742f3ab

openstack/ceilometer,openstack/ceilometer