added delete links to the microposts by adding in link_to delete tags in the micropost and feed_item partials.  both of these methods are similiar.  Not sure how they are passed around yet.
added a test for micropost destruction.  before it creates a micropost using a user and the factorygirl.create method.  then it { visit root_path } and expects to {click_link 'delete'}.to change(Micropost, :count).by(-1)
updated the micropost controller with a before_filter that called the correct_user private function to check if the micropost was owned by the current user before a destroy action was sent.  also corrected a bug in the microposts html partial.