Bugfix:
displayName was not properly initialized in ActivitySpaceMemberAdded.php
Bugfix:
Fixed problem causing the activity+content not to be created when a member joins a space.
Fixed problem causing the wrong user to be set to the created activity when a user leaves a space.
Merge pull request #79 from BastusIII/master

Fixed 3 minor bugs concerning activitiy creation + display when joining/leaving spaces