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 02:29:55PM -0800, Greg Wilson wrote:
> > +  <tr><td>badges:</td><td>{{ person.award_set.all | join:"," }}</td></tr>
> 
> 1.  Separate with ", " (comma-space) rather than just ",".

Fixed, thanks.

> 2.  Can the badges easily be made links to the pages for those
> badges (which is where criteria for the award and a list of people
> who have the badge will be displayed)?

Sure, but I don't think we have a page like that yet.  Will it be:

  /workshops/persons?badge=instructor

?  I'd rather have all of our person-listing handled by
/workshops/persons with query parameters, but we currently have an
alternative person listing at /workshops/match, and that makes it hard
to know where additional filtering logic should land.