Scaffold `Submission` Ressource

We are using the `rails g scaffold` command and let Rails do all the
heavy lifting. The following commands were used:

- rails generate scaffold Submission link:string votes:integer
- rake db:migrate
- rails s

And point your browser to localhost:3000

Also remember that we added a default value of 0 for the votes attribute
in db/migrations/2013...create_submissions.rb