Fix Apache 2.4 and add support for Ubuntu 14.10

This pull request  adds some enhancements to the Apache 2.4 support :

- Replace require_all with use_require and remove the uneeded Directory in standard.tmpl (which would end up emtpy with Apache 2.2). My motivation is that you do not want to have a Require all granted just because you are running Apache 2.4.

- Add a condition in standard.tmpl to choose Require or Order/allow accordingly to Apache version, and add default value for Require.

- Fix standard.sls regarding config files location and names on Debian/Ubuntu.