* tombstone added to schema dump
* read/write actor_definition.tombstone in config persistence
* add tombstone field when loading from yaml seed persistence
* add tombstone to normalized_tables_schema.txt
* add test to ensure tombstone defaults to false
* add release_date and release_stage to actor_definition
- migration to add columns
- update json schema to add new fields
- update API schema to include new fields in definition reads
- update tests
* rename definition creation methods to include custom
* add format:date for releaseDate, and define shared releaseStage enum
* handle null releaseDate
5da184895f