Use the Mongo starter for the sample application

See gh-1831

spring-boot-samples/spring-boot-sample-data-mongodb/pom.xml

@@ -24,8 +24,8 @@
 			<artifactId>spring-boot-starter</artifactId>
 		</dependency>
 		<dependency>
-			<groupId>org.springframework.data</groupId>
+			<groupId>org.springframework.boot</groupId>
-			<artifactId>spring-data-mongodb</artifactId>
+			<artifactId>spring-boot-starter-data-mongodb</artifactId>
 		</dependency>
 		<dependency>
 			<groupId>org.springframework.boot</groupId>