db_sync: correct logic, do not ignore failures

Simplify and correct logic to not ignore errors which may occur when
checking the db_version using the manage tools.

Also remove no longer needed exit_status module.
I went back and forth on this a lot and was trying to make it only run when the DB is created OR when `database_sync: True`. But, if we set the default to `True` then we defeat the purpose of the changed check and override support. 

I'm not much of a fan of the direct comparison either, but felt this was probably the best explicit way to disable sync for all cases.