Use thoughtbot/rcm for Homebrew

Back when rcm was an experiment by Mike Burns, the `homebrew-rcm` GitHub
repo was hosted under the `mike-burns` account. It has since been moved
to `thoughtbot` so that more may share in the love.
Change Homebrew install path

Looks like it's hosted in a different repository now.
Add command for accepting XCode agreement on Mavericks
The big refactor

Removing Ruby and other items I'm not currently using.
Moving to a Homebrew-centric flow.
Merge remote-tracking branch 'origin/thoughbot'
Add command for accepting XCode agreement on Mavericks
Change Homebrew install path

Looks like it's hosted in a different repository now.
Add Homebrew Zsh completions on install
Remove extra fi statement in homebrew setup
WIP: README - add my name to the repo install URLs
Add .DS_Store and npm-debug.log to gitignore
Update existing formulae if Homebrew is already installed
Update casks, formula, and install experience
Merge remote-tracking branch 'origin/brewfiles'