Resolve "Support optional use of Application CRD"

This adds an Application instance for clusters working with https://github.com/kubernetes-sigs/application

The labels for all resources have been centralized in a top-level template and the application label is added to everything if global.application.name is set.

Creating the actual Application can be disabled using global.application.create=false in case there is some other process handling that.

Since I was adding labels to secrets, I went ahead and handled #568 (closed) too.

Closes #568 (closed) Closes #453 (closed)