Add clarification to allocation status notifications

[djperrefort]

Some user's have reported getting confused by the allocation status emails. Specifically, they are not aware that Keystone supports awarding multiple allocations at once. I suspect this confusion will abate once web front end is GA. For now, some requests have been made regarding clarification. Specifically:

1. Include the allocation ID
2. Add a sentence / paragraph clarifying the existence of other (unaffected) allocations