use underscore instead of downcase in constructing jcropper path
use underscore instead of downcase in constructing jcropper path

to handle CamelCase model names properly
Ricardonacif/active_admin_jcrop,Ricardonacif/active_admin_jcrop,zshannon/active_admin_jcrop,zshannon/active_admin_jcrop,Ricardonacif/active_admin_jcrop,zshannon/active_admin_jcrop