Fixed warning: java: Trip.java uses unchecked or unsafe operations.
- Added validator for Email, and EmailList
- Added views for inviting people by email to a trip
- Added method for inviting people to a trip by mail
- Update of mailing services to mail multiple people at the-same time
- Update of TripController to invite people to a trip.
Simple TripService test for the invite() method -> to check if it checks mails
Simple TripService test for the invite() method -> to check if it checks mails
Added selenium pages but no tests -> No way to reach a trip page as organizer through UI