Updates to README.
Clean requirements.
Upgrading django-cms: http://docs.django-cms.org/en/latest/upgrade/3.0.htmllaurenmcman_us/settings_production.pyupgrading-from-2-4
Upgrading django-cms: http://docs.django-cms.org/en/latest/upgrade/3.0.htmllaurenmcman_us/settings.pyupgrading-from-2-4
Upgrade various dependencies.