Use hexadecimal ids and lowercase names in zipkin input (#3488)

.../inputs/zipkin/cmd/stress_test_write/stress_test_write.go

plugins/inputs/zipkin/codec/jsonV1/jsonV1.go

plugins/inputs/zipkin/codec/jsonV1/jsonV1_test.go

plugins/inputs/zipkin/codec/thrift/thrift.go

plugins/inputs/zipkin/convert.go

plugins/inputs/zipkin/convert_test.go

plugins/inputs/zipkin/handler_test.go

plugins/inputs/zipkin/zipkin_test.go