added new python and django versions and drop pypy from travis matrix
added new python and django versions and drop pypy from travis matrix

pombredanne/django-activity-stream,thelabnyc/django-activity-stream,justquick/django-activity-stream,jrsupplee/django-activity-stream,justquick/django-activity-stream,pombredanne/django-activity-stream,thelabnyc/django-activity-stream,jrsupplee/django-activity-stream