Automate remapping Caps Lock to Escape

Now that macOS 10.12.1 includes built-in remapping for Caps Lock-to-Escape, I've ditched Karabiner Elements (since that was the only thing I used it for). See: [Remapping the Caps Lock key to Escape in macOS Sierra](http://www.jeffgeerling.com/blog/2016/remapping-caps-lock-key-escape-macos-sierra)

But I'd still like to have that setting automated so I don't have to click through the Keyboard system preferences when setting up my Mac fresh.

See: [Updating modifier key mappings through defaults command tool](http://apple.stackexchange.com/a/88096/17366); the setting has to be set _per keyboard_ (in my case, I have two, an 'Apple Keyboard', and an 'Apple Internal Keyboard / Trackpad', with unique IDs. I'd have to set it up (maybe in the `.osx` bash script in my dotfiles?) to add the mapping for each keyboard detected.