BAEL-2910 MockMvc Kotlin DSL

* configured spring repo in the 'parent-kotlin' model
  to allow using spring's milestone artifacts
* configured jackson kotlin module in the 'parent-kotlin'
  to allow easy use of kotlin data classes with jackson
* switched spring-mvc-kotlin from explicit spring
  dependencies to spring-boot
* mockmvc dsl article's source and tests

parent-kotlin/pom.xml

@@ -26,6 +26,11 @@
             <id>kotlin-eap</id>
             <url>http://dl.bintray.com/kotlin/kotlin-eap</url>
         </repository>
+        <repository>
+            <id>spring-milestone</id>
+            <name>Spring Milestone Repository</name> 
+            <url>http://repo.spring.io/milestone</url> 
+        </repository>
     </repositories>
     
     <pluginRepositories>
@@ -40,7 +45,7 @@
 			<dependency>
 				<groupId>org.springframework.boot</groupId>
 				<artifactId>spring-boot-dependencies</artifactId>
-				<version>2.0.1.RELEASE</version>
+				<version>2.2.0.M4</version>
 				<type>pom</type>
 				<scope>import</scope>
 			</dependency>
@@ -80,6 +85,10 @@
 			<artifactId>ktor-gson</artifactId>
 			<version>${ktor.io.version}</version>
 		</dependency>
+		<dependency>
+			<groupId>com.fasterxml.jackson.module</groupId>
+			<artifactId>jackson-module-kotlin</artifactId>
+		</dependency>
 
 		<dependency>
 			<groupId>org.jetbrains.kotlin</groupId>