remove downloading of jpeg-recompress from travis, it will be provided by image_optim_pack
remove downloading of jpeg-recompress from travis, it will be provided by image_optim_pack

ramiroaraujo/image_optim,weheartit/image_optim,mihailim/image_optim,toy/image_optim,ramiroaraujo/image_optim,ramiroaraujo/image_optim,mihailim/image_optim,toy/image_optim,weheartit/image_optim,mihailim/image_optim,toy/image_optim,weheartit/image_optim