Initial commit with classes and a dummy test (to set the static imports of hamcrest)
Add first test: validate the user is logged in
Add second test: should not return any trips if users are not friends
refactored init in a before class
Add third test: should return trips when users are friends
refactored
refactored: implement an user builder to ease construction of users in tests
refactored TripService class
refactored: get rid of fake class TripServiceForTest by using mocks