Veraticus/Dynamoid — pull request #41 by afrojas (2012-05-09 18:41:35+00:00)
Title: Added touch method

Added AR-like touch method so now if you
```ruby
someDynamoidModel.touch
```
it will set the updated_at to now and save. Also if you
```ruby
someDynamoidModel.touch(:last_login_at)
```
it will set both updated_at and last_login_at to now and save.