Switch to homebrew cask for xquartz
Switch to homebrew cask for xquartz

Old recipe was broken on Mavericks

wendorf/sprout-osx-apps,pivotal-sprout/sprout-osx-apps,wendorf/sprout-osx-apps,pivotal-sprout/sprout-osx-apps,pivotal-sprout/sprout-osx-apps,wendorf/sprout-osx-apps