INT-3147: (3167,3173,1941) Improve MetadataStore

Previously, `MetadataStore` couldn't be configured for Twitter Adapters
- only a global one could be used.
The `metadataKey` was generated automatically with a 'difficult' value.

* Register all `MessageSource` for `SourcePollingChannelAdapter`
as beans with id based on adapter id and prefix '.source' (INT-3147)
* Polishing parser to get rid of explicit `MessageSource` beans. (INT-3147)
* Make Feed and Twitter adapters `id` attribute as required -
now it presents a `metadataKey` for `MetadataStore` (INT-3147)
* Add to Twitter adapters a reference attribute for `MetadataStore` (INT-3173)
* Add Twitter adapters `poll-skip-period` attribute (INT-3167)
* Add and implement `MetadataStore#remove` (INT-1941)
* Make `MetadataStore` as `@ManagedResource` (INT-1941)
* Polishing tests

JIRAs:
https://jira.springsource.org/browse/INT-3147
https://jira.springsource.org/browse/INT-3167
https://jira.springsource.org/browse/INT-3173
https://jira.springsource.org/browse/INT-1941

INT-3147: Polishing and fixes

* add domain suffix to `metadataKey`
* change contract of `MetadataStore.remove`
* remove timeout window from `AbstractTwitterMessageSource`
* polishing and fix `SearchReceivingMessageSourceWithRedisTests`

INT-3147: Rebasing and polishing

INT-3147: fix 'metadata' package tangle

INT-3147 Doc Polishing

spring-integration-jmx/src/test/java/org/springframework/integration/jmx/config/PollingAdapterMBeanTests-context.xml

@@ -13,18 +13,18 @@
 			http://www.springframework.org/schema/integration/jmx/spring-integration-jmx.xsd">
 
 	<context:mbean-server id="mbs" />
-	
+
 	<context:mbean-export server="mbs" default-domain="test.PollingAdapterMBean"/>
 
 	<int:channel id="testChannel" />
-	
-	<int:inbound-channel-adapter channel="testChannel" method="get">
+
+	<int:inbound-channel-adapter id="adapter" channel="testChannel" method="get">
 		<int:poller fixed-rate="5000" max-messages-per-poll="1"/>
 		<bean class="org.springframework.integration.jmx.config.PollingAdapterMBeanTests$Source"/>
 	</int:inbound-channel-adapter>
-	
+
 	<int:logging-channel-adapter channel="testChannel"/>
-	
+
 	<jmx:mbean-export id="integrationMbeanExporter" server="mbs" default-domain="test.PollingAdapterMBean"/>
 
 </beans>

spring-integration-jmx/src/test/java/org/springframework/integration/jmx/config/PollingAdapterMBeanTests.java

@@ -1,11 +1,11 @@
 /*
  * Copyright 2002-2010 the original author or authors.
- * 
+ *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
  * the License. You may obtain a copy of the License at
- * 
+ *
  * http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
  * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
  * specific language governing permissions and limitations under the License.
@@ -36,7 +36,7 @@ public class PollingAdapterMBeanTests {
 
 	@Autowired
 	private MBeanServer server;
-	
+
 	@Test
 	public void testMessageSourceMBeanExists() throws Exception {
 		// System.err.println(server.queryNames(new ObjectName("*:type=MessageSource,*"), null));