Add contributors to AUTHORS file and restructure
Add contributors to AUTHORS file and restructure

pombredanne/django-simple-history,luzfcb/django-simple-history,emergence/django-simple-history,emergence/django-simple-history,pombredanne/django-simple-history,treyhunner/django-simple-history,luzfcb/django-simple-history,treyhunner/django-simple-history