Fix for ruby 2.0

require 'simple_youtube/active_youtube' on youtube.rb

```
12:58:35 {master} ~/apps/forrocomturista$ rails s
/home/sadjow/apps/simple_youtube/lib/simple_youtube/youtube.rb:3:in `<module:Youtube>': uninitialized constant Youtube::ActiveYoutube (NameError)
	from /home/sadjow/apps/simple_youtube/lib/simple_youtube/youtube.rb:2:in `<top (required)>'
	from /home/sadjow/apps/simple_youtube/lib/simple_youtube.rb:7:in `block in <top (required)>'
	from /home/sadjow/apps/simple_youtube/lib/simple_youtube.rb:7:in `each'
	from /home/sadjow/apps/simple_youtube/lib/simple_youtube.rb:7:in `<top (required)>'
	from /home/sadjow/apps/mix-rails/mix-rails-videos/lib/mix-rails-videos.rb:2:in `<top (required)>'
	from /home/sadjow/apps/mix-rails/lib/mix-rails/videos.rb:1:in `<top (required)>'
	from /home/sadjow/apps/forrocomturista/config/application.rb:11:in `<top (required)>'
	from /home/sadjow/.rvm/gems/ruby-2.0.0-p0/gems/railties-3.2.13/lib/rails/commands.rb:53:in `require'
	from /home/sadjow/.rvm/gems/ruby-2.0.0-p0/gems/railties-3.2.13/lib/rails/commands.rb:53:in `block in <top (required)>'
	from /home/sadjow/.rvm/gems/ruby-2.0.0-p0/gems/railties-3.2.13/lib/rails/commands.rb:50:in `tap'
	from /home/sadjow/.rvm/gems/ruby-2.0.0-p0/gems/railties-3.2.13/lib/rails/commands.rb:50:in `<top (required)>'
	from script/rails:6:in `require'
	from script/rails:6:in `<main>'
```