[console] lightweight silex console

you can get the current version by calling the phar without arguments:

    $ php silex.phar
    Silex version 1ee6b36

there is only one single `update` command:

    $ php silex.phar update

this will fetch the latest version of the phar from silex-project.org
and replace the current one with it.

this makes it easier for users because they can easily update. we could
potentially even provide a changelog on running the command.

this commit also introduces a Silex\Application::VERSION constant that
currently is set to the current git SHA-1, as I proposed in PR 33. This
is done by the Compiler. It can later be adjusted to use `git describe`.

this is an implementation of PR 35 without the console component.

.gitmodules

@@ -34,3 +34,6 @@
 [submodule "vendor/monolog"]
 	path = vendor/monolog
 	url = https://github.com/Seldaek/monolog.git
+[submodule "vendor/Symfony/Component/Process"]
+	path = vendor/Symfony/Component/Process
+	url = https://github.com/symfony/Process

src/Silex/Application.php

@@ -39,6 +39,8 @@ use Silex\RedirectableUrlMatcher;
  */
 class Application extends \Pimple implements HttpKernelInterface, EventSubscriberInterface
 {
+    const VERSION = '@package_version@';
+
     /**
      * Constructor.
      */

src/Silex/Compiler.php

@@ -13,6 +13,7 @@ namespace Silex;
 
 use Symfony\Component\Finder\Finder;
 use Symfony\Component\HttpKernel\Kernel;
+use Symfony\Component\Process\Process;
 
 /**
  * The Compiler class compiles the Silex framework.
@@ -36,6 +37,7 @@ class Compiler
         $finder->files()
             ->ignoreVCS(true)
             ->name('*.php')
+            ->notName('Compiler.php')
             ->in(__DIR__.'/..')
             ->in(__DIR__.'/../../vendor/pimple')
             ->in(__DIR__.'/../../vendor/Symfony/Component/ClassLoader')
@@ -56,8 +58,8 @@ class Compiler
         $this->addFile($phar, new \SplFileInfo(__DIR__.'/../../autoload.php'));
 
         // Stubs
-        $phar['_cli_stub.php'] = $this->getStub();
-        $phar['_web_stub.php'] = $this->getStub();
+        $phar['_cli_stub.php'] = $this->getCliStub();
+        $phar['_web_stub.php'] = $this->getWebStub();
         $phar->setDefaultStub('_cli_stub.php', '_web_stub.php');
 
         $phar->stopBuffering();
@@ -75,10 +77,50 @@ class Compiler
             $content = Kernel::stripComments($content);
         }
 
+        $process = new Process('git rev-parse --short HEAD');
+        if ($process->run() > 0) {
+            throw new \RuntimeException('The git binary cannot be found.');
+        }
+        $content = str_replace('@package_version@', $process->getOutput(), $content);
+
         $phar->addFromString($path, $content);
     }
 
-    protected function getStub()
+    protected function getCliStub()
+    {
+        return <<<'EOF'
+<?php
+/*
+ * This file is part of the Silex framework.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+require_once __DIR__.'/autoload.php';
+
+$command = isset($argv[1]) ? $argv[1] : null;
+
+switch ($command) {
+    case 'update':
+        $remoteFilename = 'http://silex-project.org/get/silex.phar';
+        $localFilename = getcwd().'/silex.phar';
+
+        file_put_contents($localFilename, file_get_contents($remoteFilename));
+        break;
+
+    default:
+        echo "Silex version ".Silex\Application::VERSION."\n";
+        break;
+}
+
+__HALT_COMPILER();
+EOF;
+    }
+
+    protected function getWebStub()
     {
         return <<<EOF
 <?php

Process @ 9dce933d

+Subproject commit 9dce933d7b55f0a0df912621891955750acf102e