[VOL-2235] Mocks and interfaces for rw-core

This update consists of mocks that are used by the rw-core
during unit testing.  It also includes interfaces used for unit
tests.

Change-Id: I20ca1455c358113c3aa897acc6355e0ddbc614b7
diff --git a/vendor/go.etcd.io/etcd/client/doc.go b/vendor/go.etcd.io/etcd/client/doc.go
new file mode 100644
index 0000000..abe5199
--- /dev/null
+++ b/vendor/go.etcd.io/etcd/client/doc.go
@@ -0,0 +1,73 @@
+// Copyright 2015 The etcd 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 client provides bindings for the etcd APIs.
+
+Create a Config and exchange it for a Client:
+
+	import (
+		"net/http"
+		"context"
+
+		"go.etcd.io/etcd/client"
+	)
+
+	cfg := client.Config{
+		Endpoints: []string{"http://127.0.0.1:2379"},
+		Transport: DefaultTransport,
+	}
+
+	c, err := client.New(cfg)
+	if err != nil {
+		// handle error
+	}
+
+Clients are safe for concurrent use by multiple goroutines.
+
+Create a KeysAPI using the Client, then use it to interact with etcd:
+
+	kAPI := client.NewKeysAPI(c)
+
+	// create a new key /foo with the value "bar"
+	_, err = kAPI.Create(context.Background(), "/foo", "bar")
+	if err != nil {
+		// handle error
+	}
+
+	// delete the newly created key only if the value is still "bar"
+	_, err = kAPI.Delete(context.Background(), "/foo", &DeleteOptions{PrevValue: "bar"})
+	if err != nil {
+		// handle error
+	}
+
+Use a custom context to set timeouts on your operations:
+
+	import "time"
+
+	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+	defer cancel()
+
+	// set a new key, ignoring its previous state
+	_, err := kAPI.Set(ctx, "/ping", "pong", nil)
+	if err != nil {
+		if err == context.DeadlineExceeded {
+			// request took longer than 5s
+		} else {
+			// handle error
+		}
+	}
+
+*/
+package client