SITE_ID can now be configured via the environment.
added City model, with a default city to correspond to the default site.
allow a site's city to be edited inline in the site admin.
get rid of the Cities admin, they can only be edited through Sites now.
added directory/fixtures/chicago.json.
On second thought, don't require a city to be associated w/ a site.
Added a 'slug' field to city.

I also discovered that using call_command() to import fixtures in a
migration, as the South docs suggest, doesn't work when the model
loading the fixtures changes, since it's using the latest version of
the model rather than South's serialized orm object. So I had to
create the fixture in code instead, which is honestly more readable
anyways.
Merge branch 'multi-site' of github.com:toolness/hive-django into multi-site
changed chicago.json to have a city slug, and removed its site model.
Added city-scoped searches at `/<city-slug>/`.

This is kind of a weird commit that leaves several things in flux.

I'm trying to see if I can make this project something that can be
deployed *either* as a city-specific Hive directory *or* an umbrella site
that houses the directories of many hives, depending on whether or not
the current site (identified by settings.SITE_ID) is associated with a
City model or not.

Currently, a site is potentially both of these things at once, which
is definitely odd.

One of the things I don't like about this commit is that it removes the
use of reverse urls for /find.json and /search. Right now it looks like
this might need to be fixed at least partly through the use of a custom
template tag.
fix broken test
Add MULTI_CITY setting, city_url template tag, city_reverse().

This is a slight improvement over the last commit, which introduces the
concept of a "city URL", that is, any URL whose view name begins with
"city_". On multi-city configurations, a city URL will begin with the
slug of a city, e.g. `/nyc/`, while on non multi-city installs they
will be unprefixed. The accompanying template tag and URL resolver
take care of figuring out how the site is configured and providing the
proper URL to the caller.
get rid of settings.HIVE_CITY.
added some assertions in multi_city.py.
added multi_city context processor and used it in home.html.
change display of multi-city home page a bit, order alphabetically.
mention city name in search results if MULTI_CITY is true.
added City.shortest_name with tests.
indicate city name in user and org pages if needed.
indicate city in expertise exchange results if site is multi-city.