.osx: Use `sudo` for `systemsetup`

Closes #415.
.osx: Disable the all-too-sensitive backswipe on Chrome

Closes #416.
Merge branch 'master' of https://github.com/mathiasbynens/dotfiles

# By Lars Kappert (1) and Sindre Sorhus (1)
# Via Mathias Bynens
* 'master' of https://github.com/mathiasbynens/dotfiles:
  .osx: Disable the all-too-sensitive backswipe on Chrome
  .osx: Use `sudo` for `systemsetup`