Remove the hazard_calculation table

This is a huge change, involving the move of several method of HazardCalculation into commonlib.

PS: as a byproduct, https://bugs.launchpad.net/oq-engine/+bug/1267425 is fixed (i.e. intensity_measure_types
should not be specified when the intensity_measure_types_and_levels are specified, in the job.ini or from
the risk models).