dockerfile: upgrade to `sameersbn/ubuntu:14.04.20150603`
dockerfile: upgrade to `sameersbn/ubuntu:14.04.20150603`

tigerich/docker-redmine,hasegaw/docker-redmine,intfrr/docker-redmine,sameersbn/docker-redmine,tigerich/docker-redmine,scrapinghub/docker-redmine,patope/docker-redmine,hasegaw/docker-redmine,sameersbn/docker-redmine,patope/docker-redmine,aurlaw/docker-redmine,EvgenyKarataev/docker-redmine,petugez/docker-redmine,scrapinghub/docker-redmine,sameersbn/docker-redmine,joshuacox/docker-redmine,rewiko/docker-redmine,vladm/docker-redmine,rewiko/docker-redmine,ekulos/docker-redmine,ekulos/docker-redmine,aurlaw/docker-redmine,otsuka512/docker-redmine,otsuka512/docker-redmine,vladm/docker-redmine,otsuka512/docker-redmine,EvgenyKarataev/docker-redmine,rewiko/docker-redmine,petugez/docker-redmine,rewiko/docker-redmine,joshuacox/docker-redmine,intfrr/docker-redmine