Add type for namespaces for better UI

This adds `type Namespaces []Namespace` so that methods can be added to
this slice so that it is easier for consumers to work with the values.

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>
Implement types for namespaces

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>
Add Contains wrapper for Namespaces type

Signed-off-by: Alexander Morozov <lk4d4@docker.com>
Merge pull request #312 from LK4D4/care_#302

Add type for namespaces for better UI (replacement of #302)