INTSAMPLES-137: Add WebSockets sample

JIRA: https://jira.spring.io/browse/INTSAMPLES-137

Depends on https://github.com/spring-projects/spring-integration/pull/1274

Polishing and cleanup

* Fix `cafe-dsl` project: https://build.spring.io/browse/INTSAMPLES-NIGHTLY-JOB1-1131
* Change author emails to the `pivotal.io`
* Regenerate poms

Fix for `Cafe-DSL` sample

https://build.spring.io/browse/INTSAMPLES-NIGHTLY-JOB1-1143

basic/pom.xml

@@ -4,7 +4,7 @@
   <modelVersion>4.0.0</modelVersion>
   <groupId>org.springframework.integration.samples</groupId>
   <artifactId>basic</artifactId>
-  <version>2.2.0.BUILD-SNAPSHOT</version>
+  <version>3.0.0.BUILD-SNAPSHOT</version>
   <url>http://projects.spring.io/spring-integration</url>
   <organization>
     <name>SpringIO</name>
@@ -21,7 +21,7 @@
     <developer>
       <id>garyrussell</id>
       <name>Gary Russell</name>
-      <email>grussell@gopivotal.com</email>
+      <email>grussell@pivotal.io</email>
       <roles>
         <role>project lead</role>
       </roles>
@@ -29,7 +29,7 @@
     <developer>
       <id>markfisher</id>
       <name>Mark Fisher</name>
-      <email>mfisher@gopivotal.com</email>
+      <email>mfisher@pivotal.io</email>
       <roles>
         <role>project founder and lead emeritus</role>
       </roles>
@@ -37,12 +37,12 @@
     <developer>
       <id>ghillert</id>
       <name>Gunnar Hillert</name>
-      <email>ghillert@gopivotal.com</email>
+      <email>ghillert@pivotal.io</email>
     </developer>
     <developer>
       <id>abilan</id>
       <name>Artem Bilan</name>
-      <email>abilan@gopivotal.com</email>
+      <email>abilan@pivotal.io</email>
     </developer>
   </developers>
   <scm>