Add cascading deletes to foreign keys as well as a rule to delete large
objects when artifacts are deleted.
Deleting a run entry should delete all dependent data of that run.
- Add modules entry to TargetInfo
- When retrieving TargetInfo from cache, make sure info modules match
those for the current target, otherwise mark info as stale and
re-generate.
Update the postgres database schema:
- Rename "resourcegetters" schema to "resource_getters" for
consistency
- Rename "retreies" colum to "retry" to better relflect it purpose
- Store additional information including:
- POD serialization data
- Missing target information
- JSON formatted runstate
