Add timeout to cowboy_loop

LH: I have added a test that does both hibernate and timeout
    and fixed a related issue. I also tweaked the docs and tests.

test/handlers/loop_handler_timeout_info_h.erl

@@ -0,0 +1,23 @@
+%% This module implements a loop handler that changes
+%% the timeout value to 500ms after the first message
+%% then sends itself another message after 1000ms.
+%% It is expected to timeout, that is, reply a 299.
+
+-module(loop_handler_timeout_info_h).
+
+-export([init/2]).
+-export([info/3]).
+-export([terminate/3]).
+
+init(Req, _) ->
+	self() ! message,
+	{cowboy_loop, Req, undefined}.
+
+info(message, Req, State) ->
+	erlang:send_after(200, self(), message),
+	{ok, Req, State, 100};
+info(timeout, Req, State) ->
+	{stop, cowboy_req:reply(<<"299 OK!">>, Req), State}.
+
+terminate(stop, _, _) ->
+	ok.