Feature/add seeds

Partially using the extant code out there for blocking in this functionality, this adds a seed task to Artisan. 

`php artisan seed:make example` creates a seed with the name example at `application/seeds/example.php`.

`php artisan seed` runs all the seeds in `application/seeds/` - this could later be changed to only run specific directories within. Laravel 4 runs seeds in this cheerfully silly way - http://laravelbook.com/laravel-database-seeding/ - running all the files in `app/database/seeds`.

`php artisan seed seed-name` will run only the seed with that name. You can pass as many seed names as you like.

Once merged #68 is mostly done.

This was written so I can setup the database for load testing #175 without messing about with migrations - I can now port over all the code to the load testing branch over to this format.