carton was renamed to cask

plugins/carton/carton.plugin.zsh

-if which carton &> /dev/null
-then
-  source $(dirname $(which carton))/../etc/carton_completion.zsh
-else
-  print "zsh carton plugin: carton not found"
-fi

plugins/cask/cask.plugin.zsh

+if which cask &> /dev/null; then
+  source $(dirname $(which cask))/../etc/cask_completion.zsh
+else
+  print "zsh cask plugin: cask not found"
+fi