default_mods overreaches by implementing much more than stock OS defaults

For instance: while the mod_disk_cache module does get loaded on a stock redhat-family apache install, it's actually not enabled; the config is commented out in the httpd.conf provided by the httpd rpm.

However, the apache::mod::disk_cache class both loads the module *and* turns it on. This would undoubtedly cause some unexpected behavior for a number of sites, especially considering $apache::default_mods defaults to true. If the goal of apache::default_mods is to try and mimic a default setup for each OS flavor, then this mod should be removed from this class.

This is also true for a number of other apache mods. Fortunately, since all of the ones that should be removed are already classes, this means it will be trivial for others to selectively include them in their own modules.