CS-889 | Updated the Retweet serializer to add in generic extensions to both the actor and object. Moved more generic buildActor() function up to the base activity serializer
CS-281 | Now including the actual link to the specified tweet or retweet in the activity object. Also including generic activity extensions for retweets
CS-281 | Removed extra addTwitterExtensions function from retweet serializer
Merge pull request #18 from robdouglas/CS-281

Cs 281