Move `cask` to `cmd/`.

Library/Homebrew/brew.rb

@@ -53,9 +53,6 @@ begin
     ENV["PATH"] += "#{File::PATH_SEPARATOR}#{tap_cmd_dir}"
   end
 
-  # Add cask commands to PATH.
-  ENV["PATH"] += "#{File::PATH_SEPARATOR}#{HOMEBREW_LIBRARY}/Homebrew/cask/cmd"
-
   # Add SCM wrappers.
   ENV["PATH"] += "#{File::PATH_SEPARATOR}#{HOMEBREW_SHIMS_PATH}/scm"
 

Library/Homebrew/cask/cmd/brew-cask.rb

-require "pathname"
-
-$LOAD_PATH.unshift(File.expand_path("../../lib", Pathname.new(__FILE__).realpath))
-
-require "hbc"
-
-begin
-  Hbc::CLI.process(ARGV)
-rescue Interrupt
-  puts
-  exit 130
-end

Library/Homebrew/cmd/cask.rb

+$LOAD_PATH.unshift("#{HOMEBREW_LIBRARY_PATH}/cask/lib")
+require "hbc"
+
+module Homebrew
+  module_function
+
+  def cask
+    Hbc::CLI.process(ARGV)
+  end
+end