change the API to support only one job/calculation
change the API to support only one job/calculation


Former-commit-id: fcd00a8bcdfa7285ee305ec2ed87f3a15a6f6a83 [formerly fcd00a8bcdfa7285ee305ec2ed87f3a15a6f6a83 [formerly 9eda7e336506616b5f5f85a93ddacf378339d94f]]
Former-commit-id: fb85d1afea8fd854e1e229dd80f55a1bacd6485d
Former-commit-id: 67ce2cad280702392e98096046f15a8441935f51
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine