ikiwiki: When installing app during restore process, causes apache connection breaks

When restoring from a backup, applications are now automatically installed when their data is being restored. During this restoration, if ikiwiki is installed, the setup process involves restarting Apache. This causes the connection to break and restore process shows an error page. The restore may succeed. One way we can solve is to make the mod_cgi a core requirement and add it into Apache's setup action and remove it from ikiwiki. That way mod_cgi is always enabled but is probably okay.