Revert "Remove Composer's file and directory."

This reverts commit 5b83681411.

Symfony.gitignore

@@ -25,6 +25,7 @@
 /bin/*
 !bin/console
 !bin/symfony_requirements
+/vendor/
 
 # Assets and user uploads
 /web/bundles/
@@ -37,6 +38,9 @@
 # Build data
 /build/
 
+# Composer PHAR
+/composer.phar
+
 # Backup entities generated with doctrine:generate:entities command
 **/Entity/*~