Update federation target to etcd/clientv3 (#6119)

With CoreDNS now supporting etcdv3 as the DNS backend, we
can update our federation target to etcdv3. Users will now be
able to use etcdv3 server as the federation backbone.

Minio will update bucket data to etcdv3 and CoreDNS can pick
that data up and serve it as bucket style DNS path.

vendor/go.uber.org/multierr/CHANGELOG.md

@@ -0,0 +1,28 @@
+Releases
+========
+
+v1.1.0 (2017-06-30)
+===================
+
+-   Added an `Errors(error) []error` function to extract the underlying list of
+    errors for a multierr error.
+
+
+v1.0.0 (2017-05-31)
+===================
+
+No changes since v0.2.0. This release is committing to making no breaking
+changes to the current API in the 1.X series.
+
+
+v0.2.0 (2017-04-11)
+===================
+
+-   Repeatedly appending to the same error is now faster due to fewer
+    allocations.
+
+
+v0.1.0 (2017-31-03)
+===================
+
+-   Initial release