rename some files (#4)

diff --git a/client/iotdb_constants.go b/client/protocol.go
similarity index 100%
rename from client/iotdb_constants.go
rename to client/protocol.go
diff --git a/client/row_record.go b/client/rowrecord.go
similarity index 100%
rename from client/row_record.go
rename to client/rowrecord.go
diff --git a/client/iotdb_rpc_dataset.go b/client/rpc_dataset.go
similarity index 100%
rename from client/iotdb_rpc_dataset.go
rename to client/rpc_dataset.go