Delete check for xCode

Homebrew now checks if you're on a version of Mac OSX greater than 10.8,
if so it will install xCode Command Line tools. Since all of my machines
are currently on 10.9 and any future machine will be, it's safe to
assume [Homebrews installation][ref].

[ref]: https://github.com/Homebrew/homebrew/blob/go/install#L161

Issue: #2
Update location of Hombrew installation script

Homebrew transferred ownership from @mxcl to an official @homebrew user,
so update the location in case @github decides to deprecate redirects.

Issue: #2