Tab#with? to mirror BuildOptions#with?

Eventually a common interface could be factored out into a module, but
for now this will suffice.

Library/Homebrew/tab.rb

@@ -58,10 +58,24 @@ class Tab < OpenStruct
             :HEAD => nil
   end
 
-  def installed_with? opt
+  def with? name
+    if options.include? "with-#{name}"
+      used_options.include? "with-#{name}"
+    elsif options.include? "without-#{name}"
+      not used_options.include? "without-#{name}"
+    else
+      false
+    end
+  end
+
+  def include? opt
     used_options.include? opt
   end
 
+  def universal?
+    used_options.include? "universal"
+  end
+
   def used_options
     Options.new(super.map { |o| Option.new(o) })
   end