Refactor method of creating namespaces

[tonglil]

Instead of specifying the namespace in the configuration, that parameter should point to a K8s resource manifest template.

This would make Namespaces follow the same pattern as Secrets (.kube.sec.yml file).

Namespaces could then be created (maybe even updated via kubectl apply -f) with labels from vars:.

This functionality is asked mainly for namespace-deploy-on-pull-requests, which Drone 0.4 is not capable of, but is a functionality Drone 0.5+ is capable of.

[msuterski]

Does it mean if we were running 0.5, this feature would not be needed?

[tonglil]

@msuterski it means the opposite: this would improve Namespaces (by adding labels to them) for use by deploy on PRs, which can only be done in 0.5+.

[msuterski]

Great. Thanks