Add Spring Integration Sample

Demonstrates how `IntegrationFlow` can be exposed as a `Function`

* Upgrade to the latest dependencies

* Polishing
Resolves #214

spring-cloud-function-samples/function-sample-spring-integration/build.gradle

@@ -0,0 +1,43 @@
+buildscript {
+	ext {
+		springBootVersion = '2.1.2.RELEASE'
+	}
+	repositories {
+		mavenCentral()
+        maven { url 'https://repo.spring.io/libs-milestone' }
+	}
+	dependencies {
+		classpath("org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}")
+	}
+}
+
+apply plugin: 'java'
+apply plugin: 'eclipse'
+apply plugin: 'org.springframework.boot'
+apply plugin: 'io.spring.dependency-management'
+
+group = 'io.spring.sample'
+version = '0.0.1-SNAPSHOT'
+sourceCompatibility = 1.8
+
+repositories {
+	mavenCentral()
+    maven { url "https://repo.spring.io/milestone" }
+}
+
+
+ext {
+	springCloudFunctionVersion = '2.0.2.BUILD-SNAPSHOT'
+}
+
+dependencies {
+	implementation('org.springframework.boot:spring-boot-starter-integration')
+	implementation('org.springframework.cloud:spring-cloud-starter-function-webflux')
+	testImplementation('org.springframework.boot:spring-boot-starter-test')
+}
+
+dependencyManagement {
+	imports {
+		mavenBom "org.springframework.cloud:spring-cloud-function-dependencies:${springCloudFunctionVersion}"
+	}
+}