Remove aka warning

Library/Homebrew/formula.rb

@@ -850,17 +850,6 @@ EOF
       @skip_clean_paths or []
     end
 
-    # 'aka' is no longer used to define aliases, so have it print out
-    # a notice about the change. This will alert people with private
-    # formulae that they need to update.
-    # This notice will be removed in version 0.9
-    def aka args
-      onoe "#{name}: 'aka' is no longer used to define aliases"
-      puts "To define an alias, create a relative symlink from"
-      puts "Aliases to Formula. The name of the symlink will be"
-      puts "detected as an alias for the target formula."
-    end
-
     def keg_only reason, explanation=nil
       @keg_only_reason = KegOnlyReason.new(reason, explanation.to_s.chomp)
     end