Update Homebrew installation script

Author: shoichiaizawa

bootstrap.sh

@@ -7,7 +7,7 @@ fi
 # Download and install Homebrew
 if [[ ! -x /usr/local/bin/brew ]]; then
   echo "Info   | Install   | homebrew"
-  ruby -e "$(curl -fsSL https://raw.github.com/Homebrew/homebrew/go/install)"
+  /usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
 fi
 
 # Modify the PATH