railtie: add MIME_TYPES constant
railtie: add MIME_TYPES constant
mihailim/image_optim,ramiroaraujo/image_optim,toy/image_optim,ramiroaraujo/image_optim,mihailim/image_optim,ramiroaraujo/image_optim,toy/image_optim,toy/image_optim,mihailim/image_optim