new apps and tools

- added new osx apps
- fixed the installation of iterm
- learned about not_if
- added unix-tools

TODO:
- more apps
- more tools
- learn how to clean the cruft left in the repository after running chef-solo
- learn about templates for configuration  (though it may still be better to keep my dotfiles in a git repo by themselves, not sure).
- generalize most of these to work for multiple OSes.