fix for django-braces>=1.4.0

braces 1.3 views exported AccessMixin
in braces 1.4 this was moved views._access and not exported in views
not sure if this was the intent of braces or an oversight
if intent - should look at AccessMixin vs. using a more specific mixin

tested against django-braces 1.3.1 and django-braces 1.4.0