Add new disaggregation parameters to db/obj model

[Lars Butler]

New parameters:

LATITUDE_BIN_LIMITS = list of latitude values representing bin limits used for disaggregation, values must be in increasing order
LONGITUDE_BIN_LIMITS = list of longitude values representing bin limits for disaggregation, values must be in increasing order
MAGNITUDE_BIN_LIMITS = list of magnitude values representing bin limits for disaggregation, values must be in increasing order
EPSILON_BIN_LIMITS = list of epsilon values representing bin limits for disaggregation, values must be in increasing order
DISTANCE_BIN_LIMITS = list of distance values representing bin limits for disaggregation, values must be in increasing order
DISAGGREGATION_RESULTS = one or more of the following: 'MagPMF', 'DistPMF', 'TRTPMF', 'MagDistPMF', 'MagDistEpsPMF', 'LatLonPMF', 'LatLonMagPMF', 'LatLonMagEpsPMF', 'FullDisaggMatrix'

Lat/Lon bin limits should be limited to real lat/lon ranges (lat: [-90, +90], lon: [-180, +180]).
Each bin limit list should have at least 2 values (ascending order, no duplicates).

[Lars Butler (lars-butler)]

Pull request: https://github.com/gem/openquake/pull/519