Fix DB setup in readme

Give user permissions to create/drop databases so that `rake test`
works. Use `rake db:setup` to create dev database.
Enforce relations in the database using foreinger

We will be modifying data manually at first so let's make sure we won't
screw something up.
Add slugs using friendly_id
Display the latest question on the home page
Fix migration for adding slug to questions
Add voting

In the process add relations in the model and other minor fixes.
Add results