cog: add namespaces
This commit adds: "cog list namespaces" "cog list containers" "cog list containers nex"
By default cog list containers
will query across all container
namespaces. If a second argument is given, that argument is used
as the namespace to filter the number of containers returned.
By adding cog list namespaces
users can see which namespaces are
defined, and use this information to filter the containers they
are interested in based on the namespace.
Signed-off-by: Lincoln Thurlow lincoln@isi.edu