Make HTTP middleware easier to use

server/router/doc.go

+// Copyright 2016 The LUCI Authors. All rights reserved.
+// Use of this source code is governed under the Apache License, Version 2.0
+// that can be found in the LICENSE file.
+
+/*

[nodir, 2016/06/13 20:20:52]

I think we use // everywhere

[nishanths, 2016/06/15 18:25:08]

Done.

+Package router provides a HTTP router with support for middleware and groups.

[nodir, 2016/06/13 20:20:52]

s/a HTTP/an HTTP/

[nishanths, 2016/06/15 18:25:08]

Done.

+It wraps around julienschmidt/httprouter.
+
+Usage:
+
+        r := router.New()
+        r.Use(Logger())
+        r.GET("/", RootSpecificMiddleware(), rootHandler) // Executes Logger, RootSpecificMiddleware, rootHandler in order
+
+        authorized := r.Group("authorized")
+        authorized.Use(Authenticator(), SecondAuthMiddleware())
+        authorized.DELETE("/comment/:id", commentDeleteHandler) // Executes Logger, Authenticator, SecondAuthMiddleware, commentDeleteHandler in order (path: /authorized/comment/:id)
+
+        func rootHandler(c *router.Context) {
+                io.WriteString(c.Writer, "hello from the root route")
+        }
+
+        func Logger() router.Handler {
+                return func(c *router.Context) {
+                        log.Println("log before")
+                        c.Context = context.WithValue(c.Context, "foo", "bar")
+                        c.Next()
+                        log.Println("log after")
+                }
+        }
+*/
+package router