VOL-1460: Docker builds now use common base image.  Also Documentation Update.

Modified all docker files to use a base build that copies in vendor and
other common GOPATH items.  Then each dependant Dockerfile
uses the base and only copies in golang source needed to build.

Also grab updated lock file and vendor items missing (from a dep ensure)
for build to work.

Change-Id: I6047847c2c186a24d1f223b1a4dfab39ab381a92
diff --git a/vendor/github.com/Shopify/sarama/go.mod b/vendor/github.com/Shopify/sarama/go.mod
new file mode 100644
index 0000000..3715129
--- /dev/null
+++ b/vendor/github.com/Shopify/sarama/go.mod
@@ -0,0 +1,13 @@
+module github.com/Shopify/sarama
+
+require (
+	github.com/DataDog/zstd v1.3.5
+	github.com/Shopify/toxiproxy v2.1.4+incompatible
+	github.com/davecgh/go-spew v1.1.1
+	github.com/eapache/go-resiliency v1.1.0
+	github.com/eapache/go-xerial-snappy v0.0.0-20180814174437-776d5712da21
+	github.com/eapache/queue v1.1.0
+	github.com/golang/snappy v0.0.0-20180518054509-2e65f85255db // indirect
+	github.com/pierrec/lz4 v2.0.5+incompatible
+	github.com/rcrowley/go-metrics v0.0.0-20181016184325-3113b8401b8a
+)