Added more release notes for 0.15.1
Added more release notes for 0.15.1

rodgomes/django-waffle,rsalmaso/django-waffle,rsalmaso/django-waffle,willkg/django-waffle,rsalmaso/django-waffle,willkg/django-waffle,rsalmaso/django-waffle,rodgomes/django-waffle,rodgomes/django-waffle,rodgomes/django-waffle