GH-274: singleActiveConsumer and arbitrary args

Resolves https://github.com/spring-cloud/spring-cloud-stream-binder-rabbit/issues/274

Add support for `x-single-active-consumer` as well as setting arbitrary
arguments on queues/exchanges/bindings.

Update build version; remove temporary overrides

Resolves #276

docs/src/main/asciidoc/overview.adoc

@@ -122,7 +122,6 @@ in the format of `spring.cloud.stream.rabbit.default.<property>=<value>`.
 
 Also, keep in mind that binding specific property will override its equivalent in the default.
 
-
 acknowledgeMode::
 The acknowledge mode.
 +
@@ -248,6 +247,10 @@ dlqQuorum.initialQuorumSize::
 When `quorum.enabled=true`, set the initial quorum size.
 +
 Default: none - broker default will apply.
+dlqSingleActiveConsumer::
+Set to true to set the `x-single-active-consumer` queue property to true.
++
+Default: `false`
 dlqTtl::
 Default time to live to apply to the dead letter queue when declared (in milliseconds).
 +
@@ -274,6 +277,7 @@ Whether to create an exclusive consumer.
 Concurrency should be 1 when this is `true`.
 Often used when strict ordering is required but enabling a hot standby instance to take over after a failure.
 See `recoveryInterval`, which controls how often a standby instance attempts to consume.
+Consider using `singleActiveConsumer` instead when using RabbitMQ 3.8 or later.
 +
 Default: `false`.
 expires::
@@ -386,6 +390,10 @@ If set to `true`, the binder republishs failed messages to the DLQ with addition
 Also see the <<spring-cloud-stream-rabbit-frame-max-headroom, frameMaxHeadroom property>>.
 +
 Default: false
+singleActiveConsumer::
+Set to true to set the `x-single-active-consumer` queue property to true.
++
+Default: `false`
 transacted::
 Whether to use transacted channels.
 +
@@ -406,6 +414,13 @@ To set listener container properties that are not exposed as binder or binding p
 The binder and binding properties will be set and then the customizer will be called.
 The customizer (`configure()` method) is provided with the queue name as well as the consumer group as arguments.
 
+=== Advanced Queue/Exchange/Binding Configuration
+
+From time to time, the RabbitMQ team add new features that are enabled by setting some argument when declaring, for example, a queue.
+Generally, such features are enabled in the binder by adding appropriate properties, but this may not be immediately available in a current version.
+Starting with version 3.0.1, you can now add `DeclarableCustomizer` bean(s) to the application context to modify a `Declarable` (`Queue`, `Exchange` or `Binding`) just before the declaration is performed.
+This allows you to add arguments that are not currently directly supported by the binder.
+
 [[rabbit-receiving-batch]]
 === Receiving Batched Messages
 
@@ -581,6 +596,11 @@ When `quorum.enabled=true`, set the initial quorum size.
 Applies only when `requiredGroups` are provided and then only to those groups.
 +
 Default: none - broker default will apply.
+dlqSingleActiveConsumer::
+Set to true to set the `x-single-active-consumer` queue property to true.
+Applies only when `requiredGroups` are provided and then only to those groups.
++
+Default: `false`
 dlqTtl::
 Default time (in milliseconds) to live to apply to the dead letter queue when declared.
 Applies only when `requiredGroups` are provided and then only to those groups.
@@ -666,6 +686,11 @@ A SpEL expression to determine the routing key to use when publishing messages.
 For a fixed routing key, use a literal expression, such as `routingKeyExpression='my.routingKey'` in a properties file or `routingKeyExpression: '''my.routingKey'''` in a YAML file.
 +
 Default: `destination` or `destination-<partition>` for partitioned destinations.
+singleActiveConsumer::
+Set to true to set the `x-single-active-consumer` queue property to true.
+Applies only when `requiredGroups` are provided and then only to those groups.
++
+Default: `false`
 transacted::
 Whether to use transacted channels.
 +