fix the not working and obsolete full_name concern
This concern was actually only working in the Relatives model as is:
def full_name
"#{first_name} #{last_name}"
end
In User and Volunteer, it could only crash the app, because:
@user.profile.contact.first_name
@volunteer.contact.first_name
@relative.first_name
And, it was included into Volunteer as this, and it only didn't crash everything, because it was never used inside the Volunteer model. So remove it from Volunteer and put the working method to User and Relative.
Or in other words: it was rather a bug, then a concern ;)