Rename `CommandZ.commands` -> `CommandZ.history`
Rename `CommandZ.onChange` -> `CommandZ.onStatusChange`
Rename `handleKeyboard` -> `handleKeypress`
Store commands as history items { command: {up: ->, down: ->} }
Add `CommandZ.store()`
Add storage threshold
Add `CommandZ.reset()`
Update README
Merge pull request #2 from EtienneLem/storage

Storage mode