feat(grpc): initial grpc server. (#253)

* feat(grpc): initial grpc server.

* refactor(vendor): add missing vendor.

* fix testing

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>

vendor/google.golang.org/grpc/internal/internal.go

@@ -0,0 +1,34 @@
+/*
+ * Copyright 2016 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+// Package internal contains gRPC-internal code for testing, to avoid polluting
+// the godoc of the top-level grpc package.
+package internal
+
+// TestingCloseConns closes all existing transports but keeps
+// grpcServer.lis accepting new connections.
+//
+// The provided grpcServer must be of type *grpc.Server. It is untyped
+// for circular dependency reasons.
+var TestingCloseConns func(grpcServer interface{})
+
+// TestingUseHandlerImpl enables the http.Handler-based server implementation.
+// It must be called before Serve and requires TLS credentials.
+//
+// The provided grpcServer must be of type *grpc.Server. It is untyped
+// for circular dependency reasons.
+var TestingUseHandlerImpl func(grpcServer interface{})