More work on the Aristotle project

[micheles]

• [x] make it possible to import vulnerability functions and fragility functions together in scenario_hazard
• [ ] add an example for scenario_damage with noDamageLimit = 0 and != 0
• [x] make it possible to disable spatial correlation on demand
• [x] fix the download of uncertainty.xml.zip when the archive has an unexpected but usable format
• [ ] add a test for spatial_correlation=full
• [x] investigate the interpolation_error discovered by Petros
• [ ] add a test for cutoffed GMFs (i.e. for shakemap_id = usp0008ssb)
• [ ] add a way to disable site amplification
• [ ] add an output for the total damage distributions, similar to agglosses