Add support for using REST Assured to generate documentation snippets

This commit adds a new module, spring-restdocs-restassured, that
can be used to generate documentation snippets when testing a service
with REST Assured.

Please refer to the updated reference documentation for details.

Thanks to Johan Haleby for making a change to REST Assured so that
path parameters could be documented.

Closes gh-102

docs/src/test/java/com/example/restassured/HttpHeaders.java

@@ -0,0 +1,51 @@
+/*
+ * Copyright 2014-2016 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.restassured;
+
+import com.jayway.restassured.RestAssured;
+import com.jayway.restassured.specification.RequestSpecification;
+
+import static org.hamcrest.CoreMatchers.is;
+import static org.springframework.restdocs.headers.HeaderDocumentation.headerWithName;
+import static org.springframework.restdocs.headers.HeaderDocumentation.requestHeaders;
+import static org.springframework.restdocs.headers.HeaderDocumentation.responseHeaders;
+import static org.springframework.restdocs.restassured.RestAssuredRestDocumentation.document;
+
+public class HttpHeaders {
+
+	private RequestSpecification spec;
+
+	public void headers() throws Exception {
+		// tag::headers[]
+		RestAssured.given(this.spec)
+			.filter(document("headers",
+					requestHeaders( // <1>
+							headerWithName("Authorization").description(
+									"Basic auth credentials")), // <2>
+					responseHeaders( // <3>
+							headerWithName("X-RateLimit-Limit").description(
+									"The total number of requests permitted per period"),
+							headerWithName("X-RateLimit-Remaining").description(
+									"Remaining requests permitted in current period"),
+							headerWithName("X-RateLimit-Reset").description(
+									"Time at which the rate limit period will reset"))))
+			.header("Authroization", "Basic dXNlcjpzZWNyZXQ=") // <4>
+			.when().get("/people")
+			.then().assertThat().statusCode(is(200));
+		// end::headers[]
+	}
+}