rebase: vendor dependencies for Vault API

Uses github.com/libopenstorage/secrets to communicate with Vault. This
removes the need for maintaining our own limited Vault APIs.

By adding the new dependency, several other packages got updated in the
process. Unused indirect dependencies have been removed from go.mod.

Signed-off-by: Niels de Vos <ndevos@redhat.com>

vendor/google.golang.org/protobuf/internal/flags/flags.go

@@ -0,0 +1,24 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package flags provides a set of flags controlled by build tags.
+package flags
+
+// ProtoLegacy specifies whether to enable support for legacy functionality
+// such as MessageSets, weak fields, and various other obscure behavior
+// that is necessary to maintain backwards compatibility with proto1 or
+// the pre-release variants of proto2 and proto3.
+//
+// This is disabled by default unless built with the "protolegacy" tag.
+//
+// WARNING: The compatibility agreement covers nothing provided by this flag.
+// As such, functionality may suddenly be removed or changed at our discretion.
+const ProtoLegacy = protoLegacy
+
+// LazyUnmarshalExtensions specifies whether to lazily unmarshal extensions.
+//
+// Lazy extension unmarshaling validates the contents of message-valued
+// extension fields at unmarshal time, but defers creating the message
+// structure until the extension is first accessed.
+const LazyUnmarshalExtensions = ProtoLegacy

vendor/google.golang.org/protobuf/internal/flags/proto_legacy_disable.go

@@ -0,0 +1,9 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build !protolegacy
+
+package flags
+
+const protoLegacy = false

vendor/google.golang.org/protobuf/internal/flags/proto_legacy_enable.go

@@ -0,0 +1,9 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build protolegacy
+
+package flags
+
+const protoLegacy = true