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/github.com/streadway/amqp/README.md

@@ -0,0 +1,81 @@
+# AMQP
+
+AMQP 0.9.1 client with RabbitMQ extensions in Go.
+
+# Status
+
+*Beta*
+
+[![Build Status](https://secure.travis-ci.org/streadway/amqp.png)](http://travis-ci.org/streadway/amqp)
+
+API changes unlikely and will be discussed on [Github
+issues](https://github.com/streadway/amqp/issues) along with any bugs or
+enhancements.
+
+# Goals
+
+Provide a functional interface that closely represents the AMQP 0.9.1 model
+targeted to RabbitMQ as a server.  This includes the minimum necessary to
+interact the semantics of the protocol.
+
+# Non-goals
+
+Things not intended to be supported.
+
+  * Auto reconnect and re-synchronization of client and server topologies.
+    * Reconnection would require understanding the error paths when the
+      topology cannot be declared on reconnect.  This would require a new set
+      of types and code paths that are best suited at the call-site of this
+      package.  AMQP has a dynamic topology that needs all peers to agree. If
+      this doesn't happen, the behavior is undefined.  Instead of producing a
+      possible interface with undefined behavior, this package is designed to
+      be simple for the caller to implement the necessary connection-time
+      topology declaration so that reconnection is trivial and encapsulated in
+      the caller's application code.
+  * AMQP Protocol negotiation for forward or backward compatibility.
+    * 0.9.1 is stable and widely deployed.  Versions 0.10 and 1.0 are divergent
+      specifications that change the semantics and wire format of the protocol.
+      We will accept patches for other protocol support but have no plans for
+      implementation ourselves.
+  * Anything other than PLAIN and EXTERNAL authentication mechanisms.
+    * Keeping the mechanisms interface modular makes it possible to extend
+      outside of this package.  If other mechanisms prove to be popular, then
+      we would accept patches to include them in this pacakge.
+
+# Usage
+
+See the 'examples' subdirectory for simple producers and consumers executables.
+If you have a use-case in mind which isn't well-represented by the examples,
+please file an issue.
+
+# Documentation
+
+Use [Godoc documentation](http://godoc.org/github.com/streadway/amqp) for
+reference and usage.
+
+[RabbitMQ tutorials in
+Go](https://github.com/rabbitmq/rabbitmq-tutorials/tree/master/go) are also
+available.
+
+# Contributing
+
+Pull requests are very much welcomed.  Create your pull request on a non-master
+branch, make sure a test or example is included that covers your change and
+your commits represent coherent changes that include a reason for the change.
+
+To run the integration tests, make sure you have RabbitMQ running on any host,
+export the environment variable `AMQP_URL=amqp://host/` and run `go test -tags
+integration`.  TravisCI will also run the integration tests.
+
+Thanks to the [community of contributors](https://github.com/streadway/amqp/graphs/contributors).
+
+# External packages
+
+  * Google App Engine Dialer support: [https://github.com/soundtrackyourbrand/gaeamqp](https://github.com/soundtrackyourbrand/gaeamqp)
+  * RabbitMQ examples in Go: [https://github.com/rabbitmq/rabbitmq-tutorials/tree/master/go](https://github.com/rabbitmq/rabbitmq-tutorials/tree/master/go)
+
+# License
+
+BSD 2 clause - see LICENSE for more details.
+
+