Support voting in the java server

Support likes/votes/+1/etc in buddycloud...

Also Closes #128 

## Rules

* Same as for `<target/>` 
* Rating can be between 1 and 5
* Output MUST format as 1.0, 2.0, 3.0, 4.0, or 5.0
* You CAN NOT rate a rating post
* Post verb becomes __rated__
* Post content is overwritten to __rating: X.0__ (where X is a number between 1 and 5 inclusive)

## Example stanza

```xml

<iq from="juliet@shakespeare.lit/balcony" to="channels.shakespeare.lit" type="set" id="publish:20"> 
   <pubsub xmlns="http://jabber.org/protocol/pubsub">
      <publish node="/user/romeo@shakespeare.lit/posts">
         <item>
            <entry xmlns="http://www.w3.org/2005/Atom" xmlns:thr="http://purl.org/syndication/thread/1.0" xmlns:activity="http://activitystrea.ms/spec/1.0/" xmlns:review="http://activitystrea.ms/schema/1.0/review">
               <id>96da02ee1baef61e767742844207bec4</id>
               <title>rating</title>
               <published>2014-01-01T00:00:00.000Z</published>
               <updated>2014-01-01T00:00:00.000Z</updated>
               <author>
                  <name>juliet@shakespeare.lit</name>
                  <jid xmlns="http://buddycloud.com/atom-elements-0">juliet@shakespeare.lit</jid>
               </author>
               <content type="text">I really liked this post!</content>
               <activity:verb>rated</activity:verb>
               <activity:object>
                  <activity:object-type>post</activity:object-type>
               </activity:object>
               <thr:in-reply-to ref="1" />
               <activity:target>
                   <id>tag:channels.shakespeare.lit,/users/romeo@shakespeare.lit/posts,2</id>
                   <activity:object-type>comment</activity:object-type>
               </activity:target>
               <review:rating>5.0</review:rating>
            </entry>
         </item>
      </publish>
   </pubsub>
</iq>
```