Removed cask package

Use the CLI tool instead: `cask help`
http://cask.readthedocs.org/en/latest/
Keybinding for direx:display-item

direx:display-item kbd is C-o by default, that is shadowed by
skbd-mode (it's the prefix..) Define key in skbd-mode to bind
`C-o C-o` to direx:display-item.
This kbd works only on direx tree