WP-4254: Added School Story and Offsite Idea Story migrations. Refactored all the things.
WP-4254: Add imgur URL preparations to Image resource migration.
WP-4254: Change date format for rethink_date field.
WP-4254: Fix Byline CSV by removing header row.
WP-4255: Added Announcements migration.
WP-4255: Add Announcement migration CSV and class.
WP-4254: Fix Idea Story migration. Add School Story and Announcement real data CSV.
WP-4257: Add Ranking migration.
WP-4257: Fix Offsite Idea Story date whitespace.
WP-4257: Actually add Ranking and Offsite School Story migration data.
WP-4257: Add PR Contact field mapping.
WP-4304: Add Alt field mapping for Resource Image migration.
WP-4258: Add new Offsite Idea Story CSV data.
WP-4256: Fix doubleencoded URLs.
WP-4328: Add new data to CSV.
WP-4258: Fix Offsite School Story publication date format. Update CSVs with new data.