Component status change notification

[twagoo]

Owners of components or profiles currently are not notified proactively if their definitions depend on components that become deprecated. This would be helpful, also towards imporving/maintaining metadata quality.

Such a mechanism could either be triggered upon the actions, or could be a separate process that tracks status changes periodically and for each change do a dependency check. Either way metatada modellers also need a way of subscribing to such notifications. Currently we do not store any contact information, but in some cases it might be possible to obtain an e-mail address from the shibboleth attributes. Otherwise the user will have to provide (as is the case with display name).