Added test for the loss_fraction exporter
Added test for the loss_fraction exporter


Former-commit-id: d6eb9905679d0413bff6bcd4ecb89c523a2620ad [formerly b79f3c1c54f3b51991e961b4235f17a398cb4006]
Former-commit-id: 175177f8199f9fbc6c8fdc367bd5d310d0beac6d
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine