Added multi-store example to Spring Data REST examples.

This app demonstrates how to mix Spring Data JPA and Spring Data MongoDB together (with Spring Data REST on top) to demonstrate how to split them up properly.

rest/multi-store/src/main/java/example/treasure/Treasure.java

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+/*
+ * Copyright 2014 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package example.treasure;
+
+import lombok.Data;
+import lombok.RequiredArgsConstructor;
+
+import org.springframework.data.annotation.Id;
+import org.springframework.data.mongodb.core.mapping.Document;
+
+/**
+ * A treasure.
+ * 
+ * @author Greg Turnquist
+ * @author Oliver Gierke
+ */
+@Data
+@Document
+@RequiredArgsConstructor
+public class Treasure {
+
+	private @Id String id;
+	private final String name;
+	private final String description;
+}

rest/multi-store/src/main/java/example/treasure/TreasureRepository.java

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+/*
+ * Copyright 2014 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package example.treasure;
+
+import org.springframework.data.repository.CrudRepository;
+
+/**
+ * A repository to manage {@link Treasure}s.
+ *
+ * @author Greg Turnquist
+ * @author Oliver Gierke
+ */
+public interface TreasureRepository extends CrudRepository<Treasure, String> {}