Add Links to Pages

 - Added links to various places in the application.
Add Article Validation

 - Added required field validation for article title
 - Added minimum length for article title
 - Added displaying of validation error messages for articles
Add Editing and Use of Partial View

 - Added the ability to edit an article.
 - Added an article form partial view and updated the new and edit
   views to use the partial view.
Add Comment Creation

 - Added comment model
 - Added comment controller which handles create actions
 - Updated article view to display all comments associated with the
   article and a form for addding new comments to the article.