[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/.travis.yml b/vendor/github.com/sirupsen/logrus/.travis.yml
new file mode 100644
index 0000000..1f953be
--- /dev/null
+++ b/vendor/github.com/sirupsen/logrus/.travis.yml
@@ -0,0 +1,51 @@
+language: go
+env:
+  - GOMAXPROCS=4 GORACE=halt_on_error=1
+matrix:
+  include:
+    - go: 1.10.x
+      install:
+        - go get github.com/stretchr/testify/assert
+        - go get golang.org/x/crypto/ssh/terminal
+        - go get golang.org/x/sys/unix
+        - go get golang.org/x/sys/windows
+      script:
+        - go test -race -v ./...
+    - go: 1.11.x
+      env: GO111MODULE=on
+      install:
+        - go mod download
+      script:
+        - go test -race -v ./...
+    - go: 1.11.x
+      env: GO111MODULE=off
+      install:
+        - go get github.com/stretchr/testify/assert
+        - go get golang.org/x/crypto/ssh/terminal
+        - go get golang.org/x/sys/unix
+        - go get golang.org/x/sys/windows
+      script:
+        - go test -race -v ./...
+    - go: 1.10.x
+      install:
+        - go get github.com/stretchr/testify/assert
+        - go get golang.org/x/crypto/ssh/terminal
+        - go get golang.org/x/sys/unix
+        - go get golang.org/x/sys/windows
+      script:
+        - go test -race -v -tags appengine ./...
+    - go: 1.11.x
+      env: GO111MODULE=on
+      install:
+        - go mod download
+      script:
+        - go test -race -v -tags appengine ./...
+    - go: 1.11.x
+      env: GO111MODULE=off
+      install:
+        - go get github.com/stretchr/testify/assert
+        - go get golang.org/x/crypto/ssh/terminal
+        - go get golang.org/x/sys/unix
+        - go get golang.org/x/sys/windows
+      script:
+        - go test -race -v -tags appengine ./...