[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/gorilla/websocket/.travis.yml b/vendor/github.com/gorilla/websocket/.travis.yml
new file mode 100644
index 0000000..9f233f9
--- /dev/null
+++ b/vendor/github.com/gorilla/websocket/.travis.yml
@@ -0,0 +1,20 @@
+language: go
+sudo: false
+
+matrix:
+  include:
+    - go: 1.4
+    - go: 1.5
+    - go: 1.6
+    - go: 1.7
+    - go: 1.8
+    - go: 1.9
+    - go: tip
+  allow_failures:
+    - go: tip
+
+script:
+  - go get -t -v ./...
+  - diff -u <(echo -n) <(gofmt -d .)
+  - go vet $(go list ./... | grep -v /vendor/)
+  - go test -v -race ./...