Update rate-tree.json and mfd-map.json

This update applies the new total 10^ai and b-values for use with the new spatial PDFs. The 2018 rates differed by smoothing model, these new rates vary by decluster model. The total 10^ai annual rates are computed during the gridding/counting process, rather than converted from the N(M>=5) values, and are computed for the completeness duration (not annual).

See #25 (closed)