Made apache2-http.include.conf Apache 2.4 compatible.

Since Apache 2.4, `Require all granted` replaces the lines:

    Order allow,deny
    allow from all
This is wrapped in `<IfVersion …></IfVersion>` directives to
ensure backwards compatibility with older Apache versions than 2.4.

This should be probably double-checked and tested by one of the consultant guys.
If the tests are ok, I think it would make sense to cherry-pick it also for the upcoming 3.3.0 release as Apache 2.4 is now stable in some Linux distributions.