bumped min PHP version to 5.3.9

Author: xelaris

contributing/code/patches.rst

@@ -14,9 +14,15 @@ Before working on Symfony, setup a friendly environment with the following
 software:
 
 * Git;
-* PHP version 5.3.3 or above;
+* PHP version 5.3.9 or above;
 * `PHPUnit`_ 4.2 or above.
 
+.. caution::
+
+   Before Symfony 2.7, the minimal PHP version was 5.3.3. Please keep
+   this in mind, if you are working on a bug fix for earlier versions
+   of Symfony.
+
 Configure Git
 ~~~~~~~~~~~~~
 

cookbook/bundles/best_practices.rst

@@ -348,6 +348,13 @@ there are 3 modes, which the user can configure in their project:
 * 2.5-BC: the new 2.5 API with a backwards-compatible layer so that the
   2.4 API still works. This is only available in PHP 5.3.9+.
 
+.. note::
+
+    Starting with Symfony 2.7, the support for the 2.4 API has been
+    dropped and the minimal PHP version required for Symfony was
+    increased to 5.3.9. If your bundles requires Symfony >=2.7, you
+    don't need to take care about the 2.4 API anymore.
+
 As a bundle author, you'll want to support *both* API's, since some users
 may still be using the 2.4 API. Specifically, if your bundle adds a violation
 directly to the :class:`Symfony\\Component\\Validator\\Context\\ExecutionContext`

cookbook/deployment/azure-website.rst

@@ -96,7 +96,7 @@ and how to properly configure PHP for a production environment.
 Configuring the latest PHP Runtime
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-Even though Symfony only requires PHP 5.3.3 to run, it's always recommended
+Even though Symfony only requires PHP 5.3.9 to run, it's always recommended
 to use the most recent PHP version whenever possible. PHP 5.3 is no longer
 supported by the PHP core team, but you can update it easily in Azure.
 

reference/configuration/framework.rst

@@ -707,17 +707,17 @@ api
 Starting with Symfony 2.5, the Validator component introduced a new validation
 API. The ``api`` option is used to switch between the different implementations:
 
-``2.4``
-    Use the vaidation API that is compatible with older Symfony versions.
-
 ``2.5``
     Use the validation API introduced in Symfony 2.5.
 
 ``2.5-bc`` or ``auto``
     If you omit a value or set the ``api`` option to ``2.5-bc`` or ``auto``,
     Symfony will use an API implementation that is compatible with both the
-    legacy implementation and the ``2.5`` implementation. You have to use
-    PHP 5.3.9 or higher to be able to use this implementation.
+    legacy ``2.4`` implementation and the ``2.5`` implementation.
+
+.. note::
+
+    The support for the native 2.4 API has been dropped since Symfony 2.7.
 
 To capture these logs in the ``prod`` environment, configure a
 :doc:`channel handler </cookbook/logging/channels_handlers>` in ``config_prod.yml`` for