Add ".env" to Laravel.gitignore

Laravel 5 uses vlucas/phpdotenv for env configuration.
http://laravel.com/docs/5.0/configuration#environment-configuration
Previous version used env.php files. the new configuration files do not have
.php extension

Laravel.gitignore

@@ -1,3 +1,4 @@
 /bootstrap/compiled.php
 .env.*.php
 .env.php
+.env