Upgrade to Spring Integration 4.1.8.RELEASE

Closes gh-4719

Author: wilkinsona

spring-boot-dependencies/pom.xml

@@ -117,7 +117,7 @@
 		<spring-batch.version>3.0.6.RELEASE</spring-batch.version>
 		<spring-data-releasetrain.version>Evans-SR4</spring-data-releasetrain.version>
 		<spring-hateoas.version>0.16.0.RELEASE</spring-hateoas.version>
-		<spring-integration.version>4.1.6.RELEASE</spring-integration.version>
+		<spring-integration.version>4.1.8.RELEASE</spring-integration.version>
 		<spring-loaded.version>1.2.5.RELEASE</spring-loaded.version>
 		<spring-mobile.version>1.1.5.RELEASE</spring-mobile.version>
 		<spring-plugin.version>1.1.0.RELEASE</spring-plugin.version>