Be more verbose when users insist on being sudoers

If you google for "Cowardly refusing to sudo brew" you get a lot of confused users who didn't read any of the Homebrew documentation and then had a hissy-fit.

Library/Homebrew/cmd/install.rb

@@ -2,7 +2,7 @@ require 'formula_installer'
 require 'hardware'
 require 'blacklist'
 
-module Homebrew extend self
+module Homebrew extend self  
   def install
     raise FormulaUnspecifiedError if ARGV.named.empty?
 
@@ -15,9 +15,7 @@ module Homebrew extend self
     end unless ARGV.force?
 
     if Process.uid.zero? and not File.stat(HOMEBREW_BREW_FILE).uid.zero?
-      # note we only abort if Homebrew is *not* installed as sudo and the user
+      raise "Cowardly refusing to `sudo brew install'\n#{SUDO_BAD_ERRMSG}"
-      # calls brew as root. The fix is to chown brew to root.
-      abort "Cowardly refusing to `sudo brew install'"
     end
 
     install_formulae ARGV.formulae

Library/Homebrew/cmd/link.rb

@@ -4,9 +4,7 @@ module Homebrew extend self
     raise KegUnspecifiedError if ARGV.named.empty?
 
     if Process.uid.zero? and not File.stat(HOMEBREW_BREW_FILE).uid.zero?
-      # note we only abort if Homebrew is *not* installed as sudo and the user
+      raise "Cowardly refusing to `sudo brew link'\n#{SUDO_BAD_ERRMSG}"
-      # calls brew as root. The fix is to chown brew to root.
-      abort "Cowardly refusing to `sudo brew link'"
     end
 
     if ARGV.force? then mode = :force

Library/Homebrew/exceptions.rb

@@ -179,3 +179,11 @@ class ChecksumMismatchError < RuntimeError
     super + advice.to_s
   end
 end
+
+module Homebrew extend self
+  SUDO_BAD_ERRMSG = <<-EOS.undent
+    You can use brew with sudo, but only if the brew executable is owned by root.
+    However, this is both not recommended and completely unsupported so do so at
+    your own risk.
+  EOS
+end