Improve code structure, javadoc, and build configuration

This commit makes extensive changes to the structure of the code. It
introduces a number of separate packages to provide better separation
of the various areas of functionality. Alongside this change the project
has been renamed from spring-restdocs-core to spring-restdocs.

The build has been improved to provide support for building the samples
from the main build using the buildSamples task. While this change has
been made, the samples remain standalone projects so that their
configuration is not dependent on the main project’s build. Running
buildSamples will build the samples using both Maven and Gradle.

All of the main project’s classes now have javadoc and licence/copyright
headers.

samples/rest-notes-spring-hateoas/src/main/java/com/example/notes/IndexController.java

@@ -0,0 +1,38 @@
+/*
+ * 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 com.example.notes;
+
+import static org.springframework.hateoas.mvc.ControllerLinkBuilder.linkTo;
+
+import org.springframework.hateoas.ResourceSupport;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RequestMethod;
+import org.springframework.web.bind.annotation.RestController;
+
+@RestController
+@RequestMapping("/")
+public class IndexController {
+
+	@RequestMapping(method=RequestMethod.GET)
+	public ResourceSupport index() {
+		ResourceSupport index = new ResourceSupport();
+		index.add(linkTo(NotesController.class).withRel("notes"));
+		index.add(linkTo(TagsController.class).withRel("tags"));
+		return index;
+	}
+
+}