Activate always called on VMs unless turned off.

If an activator is present, the composition system will let the
activator control activation, otherwise the composition system will call
activate. This create a more consistent lifecycle for composed modules:
activate, beforeBind, afterBind, viewAttached, documentAttached
(,documentDetached). See the Hello sample for a demo. With an activator
present (router and modal dialog system) you also get canActivate,
canDeactivate and deactivate.