Add create tourist destination cucumber feature
Add basic TouristDestination implementation
Start to use spring for faster tests
Add required fields validation for TouristDestination

* Add cucumber test for missing description.
* Add rspec tests for missing title and description.
* Add the validation in the model.
Add factory_girl_rails gem
Improve tests for tourist_destination

* Improve the cucumber tests to correctly verify the final
  redirect on successful TouristDestination creation.
* Improve the rspec tests to use more mocking and stubbing,
  making them faster and more reliable.
Add Country model
Add link between tourist_destination and country