options: treat outdated brews as installed

`brew options --installed` will now "do the right thing".

There is getting to be a small but noticeable amount of code duplication
among commands that take options like "--installed" or "--all"; it may
be worth factoring this out into a method that will return a collection
of formula objects based on the options that are passed.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>

Library/Homebrew/cmd/options.rb

@@ -1,10 +1,15 @@
 require 'formula'
+require 'cmd/outdated'
 
 def ff
   if ARGV.include? "--all"
     Formula.all
   elsif ARGV.include? "--installed"
-    Formula.all.reject{ |f| not f.installed? }
+    # outdated brews count as installed
+    outdated = Homebrew.outdated_brews.collect{ |b| b.name }
+    Formula.all.select do |f|
+      f.installed? or outdated.include? f.name
+    end
   else
     ARGV.formulae
   end