Added basic tests for dmg dist per asset trigger
Added basic tests for dmg dist per asset trigger

not everything is working yet; need to debug


Former-commit-id: 32132256c7310b4659bcb28d3f8dcc4215522961 [formerly 9317e8d9add808e8b882b8b3347fce9825b708ba]
Former-commit-id: 495c7901310f49787a4f41e22f62ed25c1c105e5
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine