#14 Add a "Minimize Unique Resources" Allocation Rule

[Mike Kelly]

Add a allocation rule that minimizes the total number
of unique resources allocated to a particular event.
This would allow us to make use of the concurrent
allocation properties of particular slots. For
example, if Guitar can be concurrently allocated to a
resource that is allocated to Leader, then the
allocator would seek to use the same resource to fill
guitar as it used to fill leader (instead of looking
for separate resources to fill each slot).