Replace terminate/2 with terminate/3, adding a Reason

This should have been done a *long* time ago, back when I initially
added Websocket support. This is the first part of two in improving
loop handler support with regards to socket closure.

Reason may include: {normal, shutdown} for the most normal shutdown,
{normal, timeout} for a loop handler timeout shutdown, or {error, _}
if an error occured.

test/websocket_handler_init_shutdown.erl

@@ -1,21 +1,14 @@
 %% Feel free to use, reuse and abuse the code in this file.
 
 -module(websocket_handler_init_shutdown).
--behaviour(cowboy_http_handler).
 -behaviour(cowboy_websocket_handler).
--export([init/3, handle/2, terminate/2]).
+-export([init/3]).
 -export([websocket_init/3, websocket_handle/3,
 	websocket_info/3, websocket_terminate/3]).
 
 init(_Any, _Req, _Opts) ->
 	{upgrade, protocol, cowboy_websocket}.
 
-handle(_Req, _State) ->
-	exit(badarg).
-
-terminate(_Req, _State) ->
-	exit(badarg).
-
 websocket_init(_TransportName, Req, _Opts) ->
 	{ok, Req2} = cowboy_req:reply(403, Req),
 	{shutdown, Req2}.