feature #239 Rely on the new twig-pack (weaverryan)

This PR was submitted for the master branch but it was merged into the 4.4 branch instead (closes #239).

Discussion
----------

Rely on the new twig-pack

Since the purpose of the website-skeleton is to give you "all" the features a website would normally need, I think it makes sense to rely on the "twig-pack" now that it exists.

This should be transparent to new users. And existing users would now get the extra stuff in the back on a `composer update`.

Commits
-------

0f64a25 Rely on the new twig-pack

Author: fabpot

composer.json

@@ -27,7 +27,7 @@
         "symfony/serializer-pack": "*",
         "symfony/swiftmailer-bundle": "^3.1",
         "symfony/translation": "*",
-        "symfony/twig-bundle": "*",
+        "symfony/twig-pack": "*",
         "symfony/validator": "*",
         "symfony/web-link": "*",
         "symfony/yaml": "*"