logrotate: stop to set owner/group to log files
logrotate: stop to set owner/group to log files

Because it's not consistent. groonga-httpd creates log files with root
owner/group. But logrotated log files are created with groonga
owner/group.

GitHub: fix #358

Reported by jacob16bit. Thanks!!!

redfigure/groonga,groonga/groonga,cosmo0920/groonga,groonga/groonga,komainu8/groonga,redfigure/groonga,cosmo0920/groonga,groonga/groonga,kenhys/groonga,kenhys/groonga,redfigure/groonga,kenhys/groonga,hiroyuki-sato/groonga,hiroyuki-sato/groonga,hiroyuki-sato/groonga,naoa/groonga,naoa/groonga,komainu8/groonga,naoa/groonga,kenhys/groonga,redfigure/groonga,komainu8/groonga,redfigure/groonga,hiroyuki-sato/groonga,naoa/groonga,kenhys/groonga,naoa/groonga,komainu8/groonga,kenhys/groonga,cosmo0920/groonga,groonga/groonga,cosmo0920/groonga,kenhys/groonga,groonga/groonga,cosmo0920/groonga,redfigure/groonga,redfigure/groonga,redfigure/groonga,groonga/groonga,cosmo0920/groonga,groonga/groonga,naoa/groonga,hiroyuki-sato/groonga,komainu8/groonga,komainu8/groonga,cosmo0920/groonga,komainu8/groonga,hiroyuki-sato/groonga,komainu8/groonga,hiroyuki-sato/groonga,hiroyuki-sato/groonga,cosmo0920/groonga,kenhys/groonga,groonga/groonga,naoa/groonga,naoa/groonga