Manually update oh-my-zsh

When you're like me and running oh-my-zsh on mac in your iTerm console you won't get auto updates, because you just don't restart your console very often. There is a way to still get oh-my-zsh updates with running this command:

$ upgrade_oh_my_zsh

UPDATE

The method is now deprecated and there is a new command:

$ omz update

Thanks to Lopekal for the info.