Fix bug 1007838: Add views for legacy URLs.

See https://github.com/mozilla/affiliates/blob/v1.0/apps/banners/urls.py
for examples of what old banner links look like.
Bug 1007847: Migrate creation date for links.

Pulls the creation date for links during the migration process. Changes
the created field to use default=timezone.new instead of auto_now_add
so that the created date can be set when a link is created and not
overridden.

Also fixes an incorrectly frozen spec for the links table in order to
make schemamigration behave properly.
Change collect_ga_data to collect data for two days ago by default.

Since GA takes up to 24 hours to show collected data, we should run the
collect command after midnight to be able to collect data for every 
click from 24 hours ago. This means it should collect from two days ago
instead of yesterday.
Add 'today' as a valid date for the collect_ga_data command.

This will allow the dev server to collect data for the current day to
speed up testing.