Remove unused dependencies from spring-messaging

Tomcat and Jetty integration tests were moved out of spring-messaging
a very long time ago (before 4.0), but the dependencies remained
unnoticed until now.

spring-messaging/spring-messaging.gradle

@@ -14,10 +14,6 @@ dependencies {
 	optional(project(":spring-context"))
 	optional(project(":spring-oxm"))
 	optional("io.projectreactor.netty:reactor-netty")
-	optional("org.eclipse.jetty.websocket:websocket-server") {
-		exclude group: "javax.servlet", module: "javax.servlet-api"
-	}
-	optional("org.eclipse.jetty.websocket:websocket-client")
 	optional("com.fasterxml.jackson.core:jackson-databind:${jackson2Version}")
 	optional("javax.xml.bind:jaxb-api:2.3.0")
 	testCompile("javax.inject:javax.inject-tck:1")
@@ -29,11 +25,6 @@ dependencies {
 		exclude group: "org.springframework", module: "spring-context"
 	}
 	testCompile("org.apache.activemq:activemq-stomp:5.8.0")
-	testCompile("org.eclipse.jetty:jetty-webapp") {
-		exclude group: "javax.servlet", module: "javax.servlet-api"
-	}
-	testCompile("org.apache.tomcat.embed:tomcat-embed-core:${tomcatVersion}")
-	testCompile("org.apache.tomcat.embed:tomcat-embed-websocket:${tomcatVersion}")
 	testCompile("org.jetbrains.kotlin:kotlin-reflect:${kotlinVersion}")
 	testCompile("org.jetbrains.kotlin:kotlin-stdlib:${kotlinVersion}")
 	testCompile("org.xmlunit:xmlunit-matchers:2.6.2")