Allocations: configure notifications for center staff

[dsajdak]

There may be types of allocations that center staff want notifications for when they are expiring. In a perfectly automated situation, if an allocation expires the users' access to it is removed. It may be desirable to have center staff notified for some types of allocations (say purchasing storage) so that they can contact the PI before the access is removed. Ideally, the most flexible way would be to allow an attribute on a resource and on an allocation to "send staff notifications" and then have an environment variable to set the email address to send these to.