Move symfony cache component

Fix #170, Replace #177

Depends on https://github.com/FriendsOfSymfony/FOSHttpCache/pull/145

*TODO*
* [ ] Wrap up https://github.com/FriendsOfSymfony/FOSHttpCache/pull/145, tag a version and up the required version in composer.json
* [ ] Documentation (see also #178 but note that things changed since then)
@dbu the only way to avoid this BC break is to avoid the refactoring entirely. I think we can be fine with documentation here. We probably don't have many users overwriting yet (EZ Publish counts as a single user given that the change will be in the project itself, not in EZ Publish installations)