The Heroku gem has been deprecated, and Heroku recommends installing the client CLI from toolbelt.heroku.com. It's a binary, but you can install the "standalone" version (https://toolbelt.heroku.com/standalone) via wget.
* Install Homebrew before RVM.
* Fix permissions.
* Install GCC 4.2.
* Use GCC dependencies listed by RVM.
* Use RVM version 1.15.10 because RVM 1.16.0 is broken with zsh.
* Use a one-step Ruby default.
* Halt execution of the script at the point that something fails.
* Update total expected time now that `brew install qt` is faster.
* Combine scripts into one file so we don't have to duplicate or
source the `successfully` function.