couple small fixes for rails 3.1 and new rake

lib/annotate.rb

@@ -5,6 +5,7 @@ module Annotate
   def self.version
     version_file = File.dirname(__FILE__) + "/../VERSION.yml"
     if File.exist?(version_file)
+      require 'yaml'
       config = YAML.load(File.read(version_file))
       version = "#{config[:major]}.#{config[:minor]}.#{config[:patch]}"
     else
@@ -14,6 +15,7 @@ module Annotate
   
   def self.load_tasks
     if File.exists?('Rakefile')
+      require 'rake'
       load 'Rakefile'
       Dir[File.join(File.dirname(__FILE__), 'tasks', '**/*.rake')].each { |rake| load rake }
       return true