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/opencord/voltha-go/rw_core/utils/core_utils.go b/vendor/github.com/opencord/voltha-go/rw_core/utils/core_utils.go
new file mode 100644
index 0000000..1e1ed9f
--- /dev/null
+++ b/vendor/github.com/opencord/voltha-go/rw_core/utils/core_utils.go
@@ -0,0 +1,24 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package utils
+
+type DeviceID struct {
+	Id string
+}
+
+type LogicalDeviceID struct {
+	Id string
+}