PA Series Summaries

This change is for http://jira.metabroadcast.com/browse/MBST-6028

It ingests series_summary and season.season_summary into a new Brand and a
new Series items and make these equivalent to the existing ones.
Merge branch 'mbst-6387-create-extra-summary-content' into stage

* mbst-6387-create-extra-summary-content:
  PA Series Summaries