Provide support for documenting path parameters

This commit adds support for documenting a request's path parameters.
For example:

mockMvc.perform(
		get("/locations/{latitude}/{longitude}", 51.5072, 0.1275))
			.andExpect(status().isOk())
			.andDo(document("locations").withPathParameters(
					parameterWithName("latitude")
							.description("The location's latitude"),
					parameterWithName("longitude")
							.description("The location's longitude")
			));

Closes gh-86

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

@@ -18,7 +18,7 @@ package com.example;
 
 import static org.springframework.restdocs.RestDocumentation.document;
 import static org.springframework.restdocs.request.RequestDocumentation.parameterWithName;
-import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
+import static org.springframework.restdocs.RestDocumentationRequestBuilders.get;
 import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
 
 import org.springframework.test.web.servlet.MockMvc;