RSocket consumer/sink

* This RSocket consumer is using the fire-and-forget strategy of execution.
* Generating the corresponding sink.
* Addressing the original PR review comments from
  https://github.com/spring-cloud/stream-applications/pull/116

* Addressing PR review comments

* Fix README

* Addressing PR review

functions/function-dependencies/pom.xml

@@ -110,6 +110,11 @@
                 <artifactId>analytics-consumer</artifactId>
                 <version>${project.version}</version>
             </dependency>
+            <dependency>
+                <groupId>org.springframework.cloud.fn</groupId>
+                <artifactId>rsocket-consumer</artifactId>
+                <version>${project.version}</version>
+            </dependency>
             <dependency>
                 <groupId>org.springframework.cloud.fn</groupId>
                 <artifactId>cassandra-consumer</artifactId>