VOL-1558 Update vendored voltha-go and other items

Result of running dep ensure.  golang openolt now
builds.

Also update dockerfile to used specific alpine version

Change-Id: I1e5407e25bb0636a241a0650d1e44e5df567f44b
diff --git a/vendor/github.com/gyuho/goraph/doc.go b/vendor/github.com/gyuho/goraph/doc.go
new file mode 100644
index 0000000..191d299
--- /dev/null
+++ b/vendor/github.com/gyuho/goraph/doc.go
@@ -0,0 +1,2 @@
+// Package goraph implements graph data structure and algorithms.
+package goraph // import "github.com/gyuho/goraph"