updating to bootstrap 3.2.0

Made the changes to get the browseable API into Bootstrap 3. 

Addresses #1085 
Most of the failing tests are here:
>  django.template.base.TemplateSyntaxError: 'optional_logout' did not receive value(s) for the argument(s): 'user'

`optional_logout` needs the `user` parameter: 

    {% optional_logout request user %}

If you can fix that we can see what's left.