Updated models.py: stylistic changes and updated hazard calc params to be not compulsory
Updated models.py: stylistic changes and updated hazard calc params to be not compulsory


Former-commit-id: 50c2a43c94bb3af15adcbcf88a8c9e7889ec9034
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine