Add Drouet & Cotton (2015) GMPE including 2017 erratum
Add Drouet & Cotton (2015) GMPE including 2017 erratum


Former-commit-id: 39ab329c021e70cd49f84b3beb82d7b3549cd2c4
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine