Fixed the --load-curve command
Fixed the --load-curve command

When loading a hazard curve using the `--load-curve` command, the `maximum_distance` parameter is not set, even though it is a mandatory parameter. This fix sets the parameter `maximum_distance` to a default value of 1000 km, which is the same value used when loading a gmf using the `--load-gmf` command.

Former-commit-id: 498928b608849fd35ae4ce3e119a09582c766a3b [formerly bf4f8cd874021bcb1df4468967cec5ce10a92cd9]
Former-commit-id: 24866c1c5c345440d53d2eec0f9a4abe92a8b6a7
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine