Bump minimum required version of PHP to 5.3.9.

This change is needed to address a bug in older versions of PHP 5.3
affecting inheritance (see https://bugs.php.net/bug.php?id=66818).

We will most likely resort to a workaround in v1.0 to stick with the
currently required minimum version of PHP (>= 5.3.2), but v1.1 will
surely require => 5.3.9.

[ci skip]

composer.json

@@ -16,7 +16,7 @@
         }
     ],
     "require": {
-        "php": ">=5.3.2"
+        "php": ">=5.3.9"
     },
     "require-dev": {
         "phpunit/phpunit": "~4.0"

package.ini

@@ -17,7 +17,7 @@ channel     = "pear.nrk.io"
 author      = "Daniele Alessandri \"nrk\" <suppakilla@gmail.com>"
 
 [require]
-php = ">= 5.3.2"
+php = ">= 5.3.9"
 pearinstaller = "1.4.1"
 
 [roles]