Merge branch 'teacher-interface' of https://github.com/BSG-TUDelft/Utopolis into mail
Added new fields to message: from, subject and readdate. This so we can use the same message object in player-to-player messages
Changed 'from' to 'sender' because hibernate doesnt like fields named 'from'
Changed relationship structure of Player / Message. Player now has a message collection instead of Message a property called player
Mail is retrieved from the server
How do I include player in Message?
Composing new messages works
When you send a mail a sound is heard
Merge remote-tracking branch 'origin/mail'