created a micropost model
require micropost to be associated with a user
made one-many user-microposts association
made default micropost sorting descending by date
delete all associated microposts if user is deleted
forced microposts to not be empty and < 140 chars
added views for microposts
added filler for micropost data
added css for microposts
set up create and destory for microposts
edited homepage to allow posting microposts
added feed variable to user model
created proto-feed for microposts
added delete to microposts