Fixes #305

Remove old recreatedb script in favour of using the makefile.

* replaces all occurences of ``datetime.now()`` with
    ``django.utils.timezone.now()`` which returns aware or naive
    datetimes based on ``USE_TZ``
* increases ``South`` version to 0.7.6 in dependencies to make
    aware datetimes work in migrations.
* Oscar's sandbox is now configured to use aware timezones by
    default

Remove customisation which now lives in the 'demo' site.

Update makefile and docs to reflect this change.

Now using new *.oscarcommerce.com domains.

Example sites now sit in their own folder (sites) for easier
organisation.