[dfssp] Platform create user

auth/cert.go

auth/cert_test.go

dfssp/api/gRPCServices.pb.go

dfssp/api/gRPCServices.proto

dfssp/authority/rootCA.go

dfssp/authority/rootCA_test.go

dfssp/contract/contract_test.go

dfssp/main.go

dfssp/server/server.go

dfssp/templates/manager.go

dfssp/templates/verificationMail.go

dfssp/user/create.go

dfssp/user/create_test.go

dfssp/user/dummy.go

dfssp/user/user_test.go