Highlight replies from friends (Gina)

[ginatrapani]

In a post's reply listing, show replies by friends of the original poster first, then sort by follower count. This will require new fields in the tt_posts table, and is dependent on Issue #124.

Plan of Action:

• Add two int fields to tt_posts: is_reply_by_friend and is_retweet_by_friend, with values 0 or 1.
• Before a reply or a retweet is inserted into the database, set each value via a new boolean FollowDAO::isUserFriendOfAuthor($author_id, $user_id) method.
• Sort all reply and retweet listing by is_reply/retweet_by_friend first, then by follower count
• Highlight the replies and retweets which are by friends of the original poster.

[ginatrapani]

Done:
http://github.com/ginatrapani/thinktank/commit/574ba756266983e805d0cd382aab825835ca48e0