.osx: Hide some menu bar icons in OS X 10.9 Mavericks

Kudos to @kevinSuttle for finding the appropriate `plist` file!
https://github.com/mathiasbynens/dotfiles/issues/305#issuecomment-30102827

Ref. #305.
.osx: Delete some old commands that no longer work

These commands only work on outdated versions of OS X.

Ref. #305.
Merge branch 'master' of https://github.com/mathiasbynens/dotfiles

# By Mathias Bynens
# Via Mathias Bynens
* 'master' of https://github.com/mathiasbynens/dotfiles:
  .osx: Delete some old commands that no longer work
  .osx: Hide some menu bar icons in OS X 10.9 Mavericks