api: Implement bucket notification. (#2271)

* Implement basic S3 notifications through queues

Supports multiple queues and three basic queue types:

1. NilQueue -- messages don't get sent anywhere
2. LogQueue -- messages get logged
3. AmqpQueue -- messages are sent to an AMQP queue

* api: Implement bucket notification.

Supports two different queue types

- AMQP
- ElasticSearch.

* Add support for redis

vendor/gopkg.in/olivere/elastic.v3/decoder.go

@@ -0,0 +1,26 @@
+// Copyright 2012-2015 Oliver Eilhard. All rights reserved.
+// Use of this source code is governed by a MIT-license.
+// See http://olivere.mit-license.org/license.txt for details.
+
+package elastic
+
+import (
+	"encoding/json"
+)
+
+// Decoder is used to decode responses from Elasticsearch.
+// Users of elastic can implement their own marshaler for advanced purposes
+// and set them per Client (see SetDecoder). If none is specified,
+// DefaultDecoder is used.
+type Decoder interface {
+	Decode(data []byte, v interface{}) error
+}
+
+// DefaultDecoder uses json.Unmarshal from the Go standard library
+// to decode JSON data.
+type DefaultDecoder struct{}
+
+// Decode decodes with json.Unmarshal from the Go standard library.
+func (u *DefaultDecoder) Decode(data []byte, v interface{}) error {
+	return json.Unmarshal(data, v)
+}