PA Series Summaries

1) what is it? Ingests Series Summaries from PA feed.
This change is for http://jira.metabroadcast.com/browse/MBST-6028
Squashed commits

2) How does it do it?
It ingests series_summary and season.season_summary into a new Brand and a
new Series items and make these equivalent to the original ones.

3) Worries or comments?
n/a