Added stats attribute to the aggregation utility [skip hazardlib]
Added stats attribute to the aggregation utility [skip hazardlib]


Former-commit-id: bc142ff5e77f4809a909e546ad83750715137779 [formerly bc142ff5e77f4809a909e546ad83750715137779 [formerly d450eadde0489d5a9be1a0a108dd24f25f22859e]]
Former-commit-id: d48f213c45b914e9a4ab3dc262bc8e1705a18912
Former-commit-id: e86b8d9406aaa99ab405cd90216ef229c9895fb3
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine