bug #4131 Replaced old way of specifying http method by the new one (…

…Baptouuuu)

This PR was submitted for the master branch but it was merged into the 2.3 branch instead (closes #4131).

Discussion
----------

Replaced old way of specifying http method by the new one

| Q                  | A
| ---------------- | ---
| Doc fix?        | yes
| New docs?   | no
| Applies to     | 2.5+
| Fixed tickets |

Commits
-------

20b20ac fix xml to specify a method
c9bdb4a replaced old way of specifying http method by the new one

cookbook/routing/redirect_trailing_slash.rst

@@ -44,16 +44,15 @@ system, as explained below:
             defaults: { _controller: AcmeDemoBundle:Redirecting:removeTrailingSlash }
             requirements:
                 url: .*/$
-                _method: GET
+            methods: [GET]
 
     .. code-block:: xml
 
         <?xml version="1.0" encoding="UTF-8" ?>
         <routes xmlns="http://symfony.com/schema/routing">
-            <route id="remove_trailing_slash" path="/{url}">
+            <route id="remove_trailing_slash" path="/{url}" methods="GET">
                 <default key="_controller">AcmeDemoBundle:Redirecting:removeTrailingSlash</default>
                 <requirement key="url">.*/$</requirement>
-                <requirement key="_method">GET</requirement>
             </route>
         </routes>
 
@@ -72,8 +71,11 @@ system, as explained below:
                 ),
                 array(
                     'url' => '.*/$',
-                    '_method' => 'GET',
-                )
+                ),
+                array(),
+                '',
+                array(),
+                array('GET')
             )
         );