Django-cities

- Do not decorate Base subclasses with python_2_unicode_compatible. See
https://code.djangoproject.com/ticket/21198

- Added Python 3 support using
https://docs.djangoproject.com/en/dev/topics/python3/
- Added featurecode and population, contributed by Chris Vigelius (chrisv2)
- Fixed ascii slug generation based on advice by Max Arnolds
- Import of cities1000.zip now tested automatically on sqlite, postgres and
mysql (python2 only) by travis.

Upgrade instructions:

pip install -U django-cities-light
./manage.py migrate cities_light

Awesome contributions were merged:

- Fixed bug in city migration where if there were two cities in the same
country with the same name only the first would be imported. This was due
to not taking into account the region checking for the records existence
before creating a new one.
- Increase performance by caching region_id and country_id in migration
function variables.
- Added debugging flag '--verify-city-import' which cerifies city import
and print out missing cities. For debug purposes only.
- Fixed bug in city migration where if the name_ascii field is null it
would set the slug name as 'city.' It now sets it to the geoname_id.
- Added to AUTHORS: Mike Mepham, Jeff Rudokas

- Merge 22: ugettext_lazy instead of ugettext.
- Added Aaron VanDerlip to AUTHORS.
- Promoted dev status to 5 Stable.

- Bugfix: zips were not imported anymore because of a bug introduced in 2.0.6

- Don't re-extract downloaded files over and over again,
- Bugfix: removed import of pympler
- Setup travis to test that database installation works on both postgres
and mysql. It was working indeed but we just have it continuously tested
now.
- Made --force less picky on arguments