Added db purge support to delete the soft-deleted records from tables.
In case of tables 'hosts' and 'failover_segments' the decision to purge
the record is made on the basis of 'deleted' and 'deleted_at' column's
value. However in case of 'notifications' table it is decided on the
basis of 'updated_at' column's value as notifications don't have
'delete' API.
Operator can use the below command to purge the records:
"masakari-manage db purge --age_in_days <days> --max_rows <rows>"
Implements: blueprint db-purge-support
Co-author: Pooja Jadhav <pooja.jadhav@nttdata.com>
Change-Id: Id959b0e2b84d5d2587d6b70b8f695f69634a1d17
4048b1fd8e