Add command_wrapper support to sysconfig-based OSes

command_wrapper support was added in 13da3e96cc41c6b44a508faed3ed81fd88f049e9 but only for debian-based OSes, this commit also makes it work for redhat-based OSes (I've got a corresponding pull request to the packaging repo at https://github.com/Graylog2/fpm-recipes/pull/23 to make the init scripts understand it)