Issue #30 : Add S3 inbound streaming channel adapter.

Fixes GH-30 (https://github.com/spring-projects/spring-integration-aws/issues/30)

* Add S3InboundStreamingMessageSource and related S3FileInfo
* Extend spring-integration-aws-1.1.xsd with s3-inbound-streaming-channel-adapter tag.
* Add S3StreamingInboundChannelAdapterParser and s3-inbound-streaming-channel-adapter handler.
* Add S3 streaming spring tests.
* Add S3 streaming documentation to README.md.

Issue #30: Resolve code style and formatting issues

Polishing:
* Revert some `build.gradle` changes
* Add JavaDoc to the `S3FileInfo.getPermissions()`

README.md

@@ -115,6 +115,82 @@ An XML variant may look like:
 </int-aws:s3-inbound-channel-adapter>
 ````
 
+###Streaming Inbound Channel Adapter
+
+This adapter produces message with payloads of type `InputStream`, allowing S3 objects to be fetched without writing to the local file system. 
+Since the session remains open, the consuming application is responsible for closing the session when the file has been consumed. 
+The session is provided in the closeableResource header (`IntegrationMessageHeaderAccessor.CLOSEABLE_RESOURCE`). Standard framework components, such as the `FileSplitter` and `StreamTransformer` will automatically close the session.
+ 
+The following Spring Boot application provides an example of configuring the S3 inbound streaming adapter using Java configuration:
+
+````java
+@SpringBootApplication
+public class S3JavaApplication {
+
+    public static void main(String[] args) {
+        new SpringApplicationBuilder(S3JavaApplication.class)
+            .web(false)
+            .run(args);
+    }
+    
+    @Autowired
+    private AmazonS3 amazonS3;
+
+    @Bean
+    @InboundChannelAdapter(value = "s3Channel", poller = @Poller(fixedDelay = "100"))
+    public MessageSource<InputStream> s3InboundStreamingMessageSource() {    
+        S3StreamingMessageSource messageSource = new S3StreamingMessageSource(template());
+        messageSource.setRemoteDirectory(S3_BUCKET);
+        messageSource.setFilter(new S3PersistentAcceptOnceFileListFilter(new SimpleMetadataStore(),
+                                   "streaming"));    	
+    	return messageSource;
+    }
+
+    @Bean
+    @Transformer(inputChannel = "s3Channel", outputChannel = "data")
+    public org.springframework.integration.transformer.Transformer transformer() {
+        return new StreamTransformer();
+    }
+    
+    @Bean
+    public S3RemoteFileTemplate template() {
+        return new S3RemoteFileTemplate(new S3SessionFactory(amazonS3));
+    }
+
+    @Bean
+    public PollableChannel s3Channel() {
+    	return new QueueChannel();
+    }
+}
+````
+
+An XML variant may look like:
+
+````xml
+<bean id="metadataStore" class="org.springframework.integration.metadata.SimpleMetadataStore"/>
+
+<bean id="acceptOnceFilter" class="org.springframework.integration.aws.support.filters.S3PersistentAcceptOnceFileListFilter">
+	<constructor-arg index="0" ref="metadataStore"/>
+	<constructor-arg index="1" value="streaming"/>
+</bean>
+
+<bean id="s3SessionFactory" class="org.springframework.integration.aws.support.S3SessionFactory"/>
+
+<int-aws:s3-inbound-streaming-channel-adapter channel="s3Channel"
+                   session-factory="s3SessionFactory"
+                   filter="acceptOnceFilter"
+                   remote-directory-expression="'my_bucket'">
+    <int:poller fixed-rate="1000"/>
+</int-aws:s3-inbound-streaming-channel-adapter>
+````
+
+Only one of `filename-pattern`, `filename-regex` or `filter` is allowed.
+
+> NOTE: Unlike the non-streaming inbound channel adapter, this adapter does not prevent duplicates by default. 
+> If you do not delete the remote file and you wish to prevent the file being processed again, you can configure an `S3PersistentFileListFilter` in the `filter` attribute. 
+> If you don’t actually want to persist the state, an in-memory `SimpleMetadataStore` can be used with the filter. 
+> If you wish to use a filename pattern (or regex) as well, use a `CompositeFileListFilter`.
+
 ###Outbound Channel Adapter
 
 The S3 Outbound Channel Adapter is represented by the `S3MessageHandler` (`<int-aws:s3-outbound-channel-adapter>`