Emacs 23: don't require skewer or coffee-mode, which now depend on Emacs 24

See #160
Drop git-gutter-fringe, which I never use
Remove duplicated requirement of haml-mode
Make ag ignore archive-contents in this repo
Ignore /history
Use fullframe to run list-packages in a full-frame window
let emacs can edit osx-plist file
Merge remote-tarcking branch 'purcell/master'