Added post controller

I added the post controller then spent some time slamming my head
against the wall when trying to view the list of posts. I went to the
/Posts/Index page which fails because:
The model backing the 'PostContext' context has changed since the
database was created. Consider using Code First Migrations to update the
database (http://go.microsoft.com/fwlink/?LinkId=238269)
After following the link, it looks like our migration scaffolding is
worthless compared to what was automatically generated for their
tutorial. I have no solution for this problem.