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 02:36:24PM -0800, Greg Wilson wrote:
> > +def event_award(request, event_slug):
> > +    '''Create awards associated with this event.'''
> > +    event = Event.objects.get(slug=event_slug)
> > +    for badge_name, role_name in [
> > +            ('organizer', 'organizer'),
> > +            ('instructor', 'instructor'),
> > +            ]:
> > …
>
> If I understand the Django correctly, you're excluding people who
> already have the badge (e.g., organizers aren't awarded twice),
> which is correct.

Right.

> However, this isn't the logic we use right now: a person gets an
> 'instructor' badge for completing instructor training, not for
> actually teaching a workshop, so auto-generating a badge because
> someone taught a workshop isn't right.

Ok.  Is the instructor badge the only thing that's currently
associated with events then?