Initial work to drop the risk_calculation table
Added a few missing attributes and fixed the export
Fixed engine_test.py
Updated the engine server
Fixed list_calculations
Updated the field uiapi.oq_job.hazard_calculation_id
Simplified list_calculations
Removed the last reference to .calc_id
Some cleanup and added a comment
Merge pull request #1569 from gem/drop-risk-calculation

Drop risk calculation table