Add per-person award administration and per-event "Assign awards" button

Fixes #37, although see my uncertainty about the "Assign awards" logic
in the "POST /workshops/event/{slug}/award" commit message.
On Sat, Dec 27, 2014 at 02:31:00PM -0800, Greg Wilson wrote:
> > +from extra_views import CreateWithInlinesView, UpdateWithInlinesView, InlineFormSet
> 
> What is `extra_views` ?

https://pypi.python.org/pypi/django-extra-views/, as I mentioned in
the commit message for the “workshops.views: Edit awards in the
person-detail edit view” commit.