Added random_seed param in the demo
Added random_seed param in the demo

Former-commit-id: 31607df26712ad97f973c5a6207a3062b5f9967a [formerly 476d806eb4d6c26661b752216abd9c65bef5fd1c]
Former-commit-id: 522ca1d04335eeec04ce04ba569859490902e5f8
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine