Add support for reusing a snippet to document common elements

This commit updates all of the Snippet implementations that take one
or more descriptors to provide an and method that can be used to
create a new Snippet that has additional descriptors.

Closes gh-168

docs/src/test/java/com/example/SnippetReuse.java

@@ -0,0 +1,34 @@
+/*
+ * Copyright 2012-2016 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;
+
+import org.springframework.restdocs.hypermedia.LinksSnippet;
+
+import static org.springframework.restdocs.hypermedia.HypermediaDocumentation.linkWithRel;
+import static org.springframework.restdocs.hypermedia.HypermediaDocumentation.links;
+
+public class SnippetReuse {
+
+	// tag::field[]
+	protected final LinksSnippet pagingLinks = links(
+			linkWithRel("first").optional().description("The first page of results"),
+			linkWithRel("last").optional().description("The last page of results"),
+			linkWithRel("next").optional().description("The next page of results"),
+			linkWithRel("prev").optional().description("The previous page of results"));
+	// end::field[]
+
+}