db/models:

Cleaned up the `hazard_metadata` logic.
calcs/risk/classical/core:

Fixed a `loss_ratio_curve_matrix` indexing bug in `classical()`.
db/models:

Fixed the logic in Output.hazard_metadata to handle more cases.

I'm still not sure if it covers all cases (haz output or haz calc,
loss curve or loss_map, etc.), but at least this reduces crashes during
XML serialization due to missing metadata.
calcs/risk/general:

Fixed an issue where the risk engine would create mean/quantile `Output` and
`LossCurve` records for _each hazard output associated with a realization_.
This is wrong. It should create a mean container if `mean_loss_curves = true`
and 1 quantile container for each `quantile_loss_curves`.
tests/calcs/risk/event_based/core_test:

Changed some docstrings into comments, so we don't throw garbage into the
nosetests -v output.
calcs/risk/classical_bcr/core:

Safer unpacking of `output_containers` results.
calcs/risk/event_based/core:

In `output_containers`, mean and quantiles now come at the end.
calcs/risk/event_based_bcr/core:

Safer unpacking of `output_containers` results.
tests/calcs/risk/general_test:

`create_outputs` now does NOT create means and quantiles.

Before, it was creating a bunch of extra records that weren't needed.