merged branch stof/patch-3 (PR #168)

Commits
-------

cf72c220 Updated the doc for the SessionExtension
a8dfaed8 Made the default locale configurable

Discussion
----------

Made the default locale configurable

Implements the feature request by @lyrrix: https://twitter.com/#!/lyrixx/status/112489647938080768

doc/extensions/session.rst

@@ -7,6 +7,8 @@ between requests.
 Parameters
 ----------
 
+* **session.default_locale**: The locale used by default in the session.
+
 * **session.storage.options**: An array of options that is passed to the
   constructor of the ``session.storage`` service.
 

src/Silex/Extension/SessionExtension.php

@@ -32,7 +32,7 @@ class SessionExtension implements ExtensionInterface
         $this->app = $app;
 
         $app['session'] = $app->share(function () use ($app) {
-            return new Session($app['session.storage']);
+            return new Session($app['session.storage'], $app['session.default_locale']);
         });
 
         $app['session.storage'] = $app->share(function () use ($app) {
@@ -44,6 +44,10 @@ class SessionExtension implements ExtensionInterface
         if (!isset($app['session.storage.options'])) {
             $app['session.storage.options'] = array();
         }
+        
+        if (!isset($app['session.default_locale'])) {
+            $app['session.default_locale'] = 'en';
+        }
     }
 
     public function onKernelRequest($event)