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/search_aggs_bucket_children.go

@@ -0,0 +1,76 @@
+// 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
+
+// ChildrenAggregation is a special single bucket aggregation that enables
+// aggregating from buckets on parent document types to buckets on child documents.
+// It is available from 1.4.0.Beta1 upwards.
+// See: http://www.elasticsearch.org/guide/en/elasticsearch/reference/current/search-aggregations-bucket-children-aggregation.html
+type ChildrenAggregation struct {
+	typ             string
+	subAggregations map[string]Aggregation
+	meta            map[string]interface{}
+}
+
+func NewChildrenAggregation() *ChildrenAggregation {
+	return &ChildrenAggregation{
+		subAggregations: make(map[string]Aggregation),
+	}
+}
+
+func (a *ChildrenAggregation) Type(typ string) *ChildrenAggregation {
+	a.typ = typ
+	return a
+}
+
+func (a *ChildrenAggregation) SubAggregation(name string, subAggregation Aggregation) *ChildrenAggregation {
+	a.subAggregations[name] = subAggregation
+	return a
+}
+
+// Meta sets the meta data to be included in the aggregation response.
+func (a *ChildrenAggregation) Meta(metaData map[string]interface{}) *ChildrenAggregation {
+	a.meta = metaData
+	return a
+}
+
+func (a *ChildrenAggregation) Source() (interface{}, error) {
+	// Example:
+	//	{
+	//    "aggs" : {
+	//      "to-answers" : {
+	//        "children": {
+	//          "type" : "answer"
+	//        }
+	//      }
+	//    }
+	//	}
+	// This method returns only the { "type" : ... } part.
+
+	source := make(map[string]interface{})
+	opts := make(map[string]interface{})
+	source["children"] = opts
+	opts["type"] = a.typ
+
+	// AggregationBuilder (SubAggregations)
+	if len(a.subAggregations) > 0 {
+		aggsMap := make(map[string]interface{})
+		source["aggregations"] = aggsMap
+		for name, aggregate := range a.subAggregations {
+			src, err := aggregate.Source()
+			if err != nil {
+				return nil, err
+			}
+			aggsMap[name] = src
+		}
+	}
+
+	// Add Meta data if available
+	if len(a.meta) > 0 {
+		source["meta"] = a.meta
+	}
+
+	return source, nil
+}