Fix tweet atom feed link to_param

Currently, a feed item appears as

    <entry>
      <id>tag:rubyfriends.com,2005:Tweet::FeedPresenter/661</id>
      <link rel="alternate" type="text/html" href="http://rubyfriends.com/tweets/%23%3CTweet::FeedPresenter:0x00000004e00958%3E"/>
      <url>pic.twitter.com/Mnd79BwB30</url>

With this patch, it will show

    <entry>
      <id>tag:rubyfriends.com,2005:Tweet::FeedPresenter/661</id>
      <link rel="alternate" type="text/html" href="http://rubyfriends.com/tweets/661/>
      <url>pic.twitter.com/Mnd79BwB30</url>

We might want to modify the class that the present returns so the `id` element doesn't have the presenter class name in it.

Note: I switched from using method_missing (without super!) to whitelisted forwardable attributes