Update homebrew install url

I got the following output after trying to install maximum-awesome on a machine without homebrew.

$ rake

-- Homebrew --------------------------------------------------------------------
Whoops, the Homebrew installer has moved! Please instead run:

ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"

Also, please ask wherever you got this link from to update it to the above.
Thanks!

-- Homebrew Cask ---------------------------------------------------------------
sh: brew: command not found
sh: brew: command not found
Failed to tap caskroom/homebrew-cask in Homebrew.
Merge pull request #175 from vinnyliao/patch-1

update homebrew installer url to https://raw.githubusercontent.com/Homebrew/install/master/install
Merge branch 'master' of https://github.com/square/maximum-awesome