bug #276 Fixed some issues for the self-update command (smatyas)

This PR was merged into the 1.0-dev branch.

Discussion
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Fixed some issues for the self-update command

Currently, the `self-update` command does not return an alerting enough exit message or status code on permission errors.
I saw in the code that it was intended, but it did not work well enough.

This PR fixes this issue by modifying the thrown exception type in certain cases, and by making the fallback exception to return error code 1, and by coloring the rollback message.

Before:
![image](https://cloud.githubusercontent.com/assets/534550/18207370/447a9004-712b-11e6-99f9-78bc05529dc9.png)

After:
![image](https://cloud.githubusercontent.com/assets/534550/18207382/5530b4be-712b-11e6-9763-e18fe4fdf6cf.png)

Commits
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ab6cce2 Fixed some issues for the self-update command: added coloring to the rollback message, set return code at general exception handling, fixed an undefined variable notice.

Author: javiereguiluz

src/Symfony/Installer/DownloadCommand.php

@@ -520,6 +520,7 @@ protected function getExecutedCommand()
         }
 
         $commandName = $this->getName();
+        $commandArguments = '';
 
         if ('new' === $commandName) {
             $commandArguments = sprintf('%s %s', $this->projectName, ('latest' !== $this->version) ? $this->version : '');

src/Symfony/Installer/SelfUpdateCommand.php

@@ -136,6 +136,8 @@ protected function execute(InputInterface $input, OutputInterface $output)
             if ($this->output->isVeryVerbose()) {
                 $this->output->writeln($e->getMessage());
             }
+
+            return 1;
         }
     }
 
@@ -148,11 +150,11 @@ private function downloadNewVersion()
     {
         // check for permissions in local filesystem before start downloading files
         if (!is_writable($this->currentInstallerFile)) {
-            throw new \RuntimeException('Symfony Installer update failed: the "'.$this->currentInstallerFile.'" file could not be written');
+            throw new IOException('Symfony Installer update failed: the "'.$this->currentInstallerFile.'" file could not be written');
         }
 
         if (!is_writable($this->tempDir)) {
-            throw new \RuntimeException('Symfony Installer update failed: the "'.$this->tempDir.'" directory used to download files temporarily could not be written');
+            throw new IOException('Symfony Installer update failed: the "'.$this->tempDir.'" directory used to download files temporarily could not be written');
         }
 
         if (false === $newInstaller = $this->getUrlContents($this->remoteInstallerFile)) {
@@ -225,7 +227,7 @@ private function rollback()
     {
         $this->output->writeln(array(
             '',
-            'There was an error while updating the installer.',
+            '<error>There was an error while updating the installer.</error>',
             'The previous Symfony Installer version has been restored.',
             '',
         ));