Merge pull request #37 from ospreys-2014/user_profile_bex

User profile bex
update spec for article model
update articles migration
update model associations
udpate specs for Topic
add topics migration
udpate topic specs
update topcis table with article_id
add Topic model
update models for topics association
update specs
update aritcle model
fix articles_controllers and views
update seed file
Merge pull request #38 from ospreys-2014/change_article_associations_xiran

Change article associations xiran
Added My Profile link in nav bar for logged in users
Created article methods for content preview, recent, and popular articles
Was working in wrong file, moved methods to model.
Working content_preview method, changed recent and popular to class methods
Working recent method, changed index route for articles to show only recent articles