Packagenameempty

this patch add support for hosts that don't need to manage the installation of ntp.  in the current version of this module, it breaks on freebsd when using pkgng as the package provider because there is no 'net/ntp' package (there's only a port).  also, since ntp is part of base freebsd, installing it is not necessary.  instead of patching only for freebsd, this patch allows any OS to skip the install class.