[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/go.etcd.io/bbolt/Makefile b/vendor/go.etcd.io/bbolt/Makefile
new file mode 100644
index 0000000..2968aaa
--- /dev/null
+++ b/vendor/go.etcd.io/bbolt/Makefile
@@ -0,0 +1,38 @@
+BRANCH=`git rev-parse --abbrev-ref HEAD`
+COMMIT=`git rev-parse --short HEAD`
+GOLDFLAGS="-X main.branch $(BRANCH) -X main.commit $(COMMIT)"
+
+default: build
+
+race:
+	@TEST_FREELIST_TYPE=hashmap go test -v -race -test.run="TestSimulate_(100op|1000op)"
+	@echo "array freelist test"
+	@TEST_FREELIST_TYPE=array go test -v -race -test.run="TestSimulate_(100op|1000op)"
+
+fmt:
+	!(gofmt -l -s -d $(shell find . -name \*.go) | grep '[a-z]')
+
+# go get honnef.co/go/tools/simple
+gosimple:
+	gosimple ./...
+
+# go get honnef.co/go/tools/unused
+unused:
+	unused ./...
+
+# go get github.com/kisielk/errcheck
+errcheck:
+	@errcheck -ignorepkg=bytes -ignore=os:Remove go.etcd.io/bbolt
+
+test:
+	TEST_FREELIST_TYPE=hashmap go test -timeout 20m -v -coverprofile cover.out -covermode atomic
+	# Note: gets "program not an importable package" in out of path builds
+	TEST_FREELIST_TYPE=hashmap go test -v ./cmd/bbolt
+
+	@echo "array freelist test"
+
+	@TEST_FREELIST_TYPE=array go test -timeout 20m -v -coverprofile cover.out -covermode atomic
+	# Note: gets "program not an importable package" in out of path builds
+	@TEST_FREELIST_TYPE=array go test -v ./cmd/bbolt
+
+.PHONY: race fmt errcheck test gosimple unused