[VOL-2193] Create mocks for Kafka Client and Etcd

This commit consists of:
1) A kafka client mock that implements the kafka client interface
under voltha-lib-go/pkg/kafka/client.go
2) An embedded Etcd server that runs in-process and represents an
Etcd server.

Change-Id: I52a36132568e08c596bb4136918bebcb654a3b99
diff --git a/vendor/github.com/sirupsen/logrus/terminal_check_notappengine.go b/vendor/github.com/sirupsen/logrus/terminal_check_notappengine.go
new file mode 100644
index 0000000..cf309d6
--- /dev/null
+++ b/vendor/github.com/sirupsen/logrus/terminal_check_notappengine.go
@@ -0,0 +1,19 @@
+// +build !appengine,!js,!windows
+
+package logrus
+
+import (
+	"io"
+	"os"
+
+	"golang.org/x/crypto/ssh/terminal"
+)
+
+func checkIfTerminal(w io.Writer) bool {
+	switch v := w.(type) {
+	case *os.File:
+		return terminal.IsTerminal(int(v.Fd()))
+	default:
+		return false
+	}
+}