Upgrading server dependancies (#4566)

vendor/github.com/gorilla/mux/doc.go

@@ -47,6 +47,10 @@ variable will be anything until the next slash. For example:
 	r.HandleFunc("/articles/{category}/", ArticlesCategoryHandler)
 	r.HandleFunc("/articles/{category}/{id:[0-9]+}", ArticleHandler)
 
+Groups can be used inside patterns, as long as they are non-capturing (?:re). For example:
+
+	r.HandleFunc("/articles/{category}/{sort:(?:asc|desc|new)}", ArticlesCategoryHandler)
+
 The names are used to create a map of route variables which can be retrieved
 calling mux.Vars():
 
@@ -136,6 +140,31 @@ the inner routes use it as base for their paths:
 	// "/products/{key}/details"
 	s.HandleFunc("/{key}/details", ProductDetailsHandler)
 
+Note that the path provided to PathPrefix() represents a "wildcard": calling
+PathPrefix("/static/").Handler(...) means that the handler will be passed any
+request that matches "/static/*". This makes it easy to serve static files with mux:
+
+	func main() {
+		var dir string
+
+		flag.StringVar(&dir, "dir", ".", "the directory to serve files from. Defaults to the current dir")
+		flag.Parse()
+		r := mux.NewRouter()
+
+		// This will serve files under http://localhost:8000/static/<filename>
+		r.PathPrefix("/static/").Handler(http.StripPrefix("/static/", http.FileServer(http.Dir(dir))))
+
+		srv := &http.Server{
+			Handler:      r,
+			Addr:         "127.0.0.1:8000",
+			// Good practice: enforce timeouts for servers you create!
+			WriteTimeout: 15 * time.Second,
+			ReadTimeout:  15 * time.Second,
+		}
+
+		log.Fatal(srv.ListenAndServe())
+	}
+
 Now let's see how to build registered URLs.
 
 Routes can be named. All routes that define a name can have their URLs built,