Updated version number on master instead of develop.
Added prepopulating of slug field based on title when creating an
adzone.
Added an expiry date for ads as well as a management command
to disable the ads once the expire.
Management command can be run from the commandline or scheduled
via a cronjob.
Removed the version number. Should have only be added to the
Master branch.
Merge branch 'ad-expiry-date' into develop